Beta Slic3r Prusa Edition Customized Supports

The most recent beta (1.42+) versions of Slic3r PE (Prusa Edition) now include more intuitive controls for customized supports. You can download the latest build of Slic3r PE from GitHub.

You are now able to add primitive shapes like cube, sphere, cylinder, etc. You can manipulate the shapes by scaling, rotating, and moving them on X, Y, and Z. This allows more fine tuning of what supports you do and do not want to include.

The horse model below has elements that need supports and elements that most likely do not need supports.

STL without supports

You can see what the default settings produce in terms of supports below. There are supports across almost the entire bottom of the horse as well as some for the mane and ears.

STL with default supports

By adding some primitive shapes as support blockers we tell Slic3r where we do not want supports.

Menu to choose adding a support blocker
Adding a single cube as a blocker

Manipulating that element lets you move and change its size and place it exactly where you want to block supports from being generated.

Manipulating cube for blocker
Manipulating cube for blocker

Once you’ve placed your support blocking element you can add more until you get the supports that suit your needs.

All blockers are in place

The end results, after slicing, are supports exactly where you want them rather than relying on Slic3r’s best guess of where supports are needed. This can save plastic, but more importantly, it reduces the amount of work you need to do after finishing the print. Supports can also leave rough surfaces on models that you print.

With blockers now showing the supports and how they've been reduced

Sometimes things go wrong

If you frequent YouTube 3D makers or forums where people show off amazing prints it can be frustrating sometimes to have a string of failures while others are creating great things. What you should remember, especially if you are new to 3D printing, prints do not work like other consumer products. A great deal of tweaking takes place to get successful prints.

Barring some catastrophic printer problems you should not give up because each failure is an oppertunity to learn more and improve your printing skills. There is almost always a reasonable and fixable solution to any problem you encounter printing.

As an example, I recent designed a model for a power supply that not only took several iterations to perfect, but when it came to printing the final design I had repeated print failures. These were 5hr plus prints so often it was 3-5 hours of wasted print time and materials.

My first test print was in PLA to check dimensions. PLA is easy to print and the test came out decent. I printed this fast just to line up the print to the real power supply.

PLA print test version
PLA test print

For a power supply cover, however, I wanted to use PETG/PET so I made changes to my model and printed the next one in PET. This resulted in bed warping and a significant crack in an important part of the model. During this print the filament runout sensor triggered despite having filament pausing the print which may have lead to the layer separation. That is three major issues on one print.

PETG print with crack
Cracked PETG print

Third print. This one warped badly on both sides so I stopped the print early because it was well on its way to failure.

Badly warped edges forced me to cancel the print

Fourth print. Everything went great until 3/4ths up a nozzle jam resulted in significant under extrusion.

Clogged nozzle results
This is what a clogged nozzle print  looks like

Quick aside: The nozzle not only jammed but cold pulling filament did not fix the issue. The jam was at the tip of the nozzle and no amount of cold pulls were getting the filament to flow better until I used a acupuncture pin to push up into the headed nozzle. Subsequent cold pulls pulled out the debris and the jam was cleared.

The final print, while not perfect (as you can see from two of the layers), did not warp, did not crack, and there were no significant nozzle issues.

Final print
Final usable print

Some of the things learned from these prints:

  • It takes time to find the right settings for new print material. I have printed with PET/G before, but this was a new brand and it turns out it needed more heat from the heated bed than the manufacturer recommended and more fine tuning of the first layer.
  • If something goes wrong try and figure out what the issue is before attempting a new print. I’ll be the first to admit that sometimes prints fail for no good reason, but it is rare. Usually there is a reason and you’ll save frustration, time, and materials if you can narrow down the cause from one print to the next.
  • PLA is easy to print with, but other materials can be harder and take more tweaking. Before you print with materials other than PLA, make sure you have your printer making great PLA prints first.

Commissioning 3D prints from hobby printers

You might not own a 3D printer, but you may want or need something printed. There are a number of commercial printing services that allow you to upload a model and have them print it in a number of different materials. Despite either having or sourcing massive printer farms these services are often the most expensive option for your one-off print.

Print farms are designed to print a large number of models usually at a single quality. Anything custom is going to cost more like changing layer height, infill, material, or print speed.

You might want to consider finding a hobby or semi-professional printer instead of a print farm. Before you do that you should know the limitations of FDM/FFF printers. These are printers that lay each plastic layer one at a time building up from the bed of the printer.

Some models are simply not printable

This is especially true for 3D models that were not designed for 3D printing to begin with. Some models can visually look fine but have thousands of errors for a 3D printer. The best models are solid or water tight (but does not have to hold water). This means there are no gaps between inner and outer walls of the model. It also means there are no 3D elements of the model that either are separated by an air gap, or improperly merged so the model contains crossed over geometry.

Extremely small models could lose detail or simply fail to print. Very large models may not fit on the printer without cutting it into multiple pieces.

Very complex models may result in repeatedly failed prints or just be too complex for software to figure out how to print it in layers.

You cannot print clear on FDM/FFF

There are clear or semi translucent filaments available, but a printer will never be able to print glass clear. The nature of melting plastic layers together reduces transparency. There are some post print techniques that can get more transparency but it will never be clear.

Some materials cannot be used outside

PLA will eventually breakdown or crack in direct sunlight. This is the most common, easiest to print, and one of the cheapest print materials so a lot of people use it as their go-to material. Other plastics may hold up better but almost all of them will fade, change color, or completely lose their color.

Printed parts should never be used when safety is needed

This means you should never use a 3D printed plastic part where someone’s health and safety is reliant on that part not failing. Some obvious examples would be rock climbing gear or functional car parts.

This extends to food safety as well. Because printers put each layer down prints have many microscopic holes that bacteria could get into. It is almost impossible to clean these parts fully. You might, however, be able to apply a post print coating that could make printed parts food safe.

Some materials and colors show layer lines more than others

Typically white or shiny colors will show printed layer lines giving you the impression that the print is worse than the same model printed in another color. Semi translucent materials hide pint layers well, and some colors just naturally hide these lines better. Some of this can be mitigated with smaller print layers (significantly adding more time to the print), but the reality is, even on the absolute best print, you will see print lines if you look close enough. Post sanding and finish work can all but eliminate these layer lines.

Most hobby printers do not have multi-color capability

And even if they do expect these prints to cost significantly more due to increased print time, more prone to failure, and increased material for color changes. Most 3D models you find online will not be multi-color ready.


  • Find a local printer. This means faster turn around and minimal or no shipping costs. It also allows you to establish a relationship with someone local if you find yourself needing another print in the future.
  • Ask for well lit high resolution pictures of the printer’s other prints. If possible, be specific and ask for images of the same material, color, and print settings. This gives you a better idea of what to expect.
  • Some prints (like figurines) will require a huge amount of support material. Detailed models will need significant clean up time which can add to the cost.
  • You should expect your hobby printer to give you an accurate quote. All print software can estimate time and material use.
  • Be understanding of delays. 3D printing is not at the paper printer point. They are more likely to run into problems than most other appliances. Failed prints can be the printer owner’s fault, but a lot of the time it can also be poorly manufactured materials, errors from the software creating the print, and other issues outside of a printer’s control.
  • Do not accept clearly awful prints. Use the example pictures, suggested above, as a benchmark.
  • If you want a model modified expect to pay a lot more. 3D modeling is not easy and takes a lot of time to learn. Not all hobby printers can make changes, but those that can will charge a high rate by the hour (expect between $40 and $150 an hour).
  • If you want a model designed from the ground up to your specifications expect not only to pay for that modeling time noted above, but also expect to go through at least 3 iterations before you get a final model. Even more iterations may be needed for a functional part. You should expect to pay for every iteration. No one will be able to design and print the prefect model the first time.
  • Consider offering a barter for 3D prints. Some people are good at modeling and printing but might lack the painting and finishing skills. This is a great opportunity to help a fellow maker and limit both your costs.

Rusting Iron Filament

Proto-Pasta makes some really interesting filament hybrids including copper, brass, steel, and iron. PLA is mixed with metallic dust to create something around 70%-85% plastic and the rest metal dust.

For the iron Proto-Pasta it means you get two added properties over normal PLA.

  • Magnets are able to stick to iron filament prints
  • Iron is prone to rusting and you can achieve a rustic or aged effect by purposefully rusting your prints


Prints that allow magnets to stick to them are as easy as simply printing a model with at least 15% infill. The magnet needs to be fairly strong, but does not need to be rare earth type magnet.


To achieve a rusted look for iron prints you need water, salt, and time. You can create a wide variety of rusted looks depending on how long and what parts of the print you expose to the water-salt mixture.

I printed the, now famous in the 3D printing world, Aria the Dragon by Loubie, in the Proto-Pasta iron fill PLA.

Iron filled PLA before rusting

Before starting the process of rusting the print I used some steel wool and light sanding to expose more of the iron dust elements in the print. Next I combined warm water and salt in a bowl with the dragon print. I used a paper towel to keep the tops of the print moist and put some lightly wrapped plastic wrap over the whole thing to try and keep it from drying out too quickly.

Salt and water bath to rust the print
Salt and water bath to rust the print

After about 13-15 hours and some air drying I achieved the light rusting effect I was going for.

Dragon with light rust

Dragon with light rust

The longer you leave the print in the salt water solution the more it will rust. Some people have been able to accelerate the process and even make entirely rusted models with other solutions. Just make sure you take proper precautions when mixing chemicals other than just salt and water.

If you plan to try printing with iron filled PLA be sure to use a hardened nozzle or the Olsson Ruby tipped nozzle. The normal brass nozzle tips will get worn down with metal filled filament.

Update on Pulse Layer Shifting

After watching the Pulse printer from MatterHackers go through a number of prints I thought the Z frame wobbled quite a bit compared to other printers. I saw this happening even at fairly slow print speeds.

Just as an experiment I decided to try and secure the Z frame during printing with a custom bracket (3D Printed of course).

Pulse Z bracket

I essentially stabilized the Z frame by attaching the bracket to a nearby stable shelf. The plastic on the right of the bracket between the shelf is just a shim to get it as stable as possible. The bracket is then screwed into the shelf.

The resulting prints are significantly better. The picture below has two prints from the Pulse that use the exact same gcode and filament. One is with the bracket (left) and the other is without the bracket (right).

Comparison print

You can see the worst of the layer shifts are significantly better, and in some cases they completely disappear.

I think other cartesian printers mitigate this issue by securing the power supply to the Z and Y frame, but because the Pulse has an unattached power supply (which is great for enclosure printing) the Z frame reacts more to movement. The Pulse has the filament spool holder in the place other printers might have a power supply, but it does not seem to provide enough stability, especially with tall and thin prints.

If you have a similar setup you are welcome to download the STL file and customize it for your needs:

Specialty Filaments – Steelfill and Brassfill

In addition to all the plastic filaments out there (ABS, PLA, PET/G, Nylon, TPU, etc) there are some speciality filaments that mix plastic (often PLA) with another material. The added material can be metal, wood, cork, glow-in-the-dark additive, pine needles, carbon fiber, and even coffee. Today I am looking at my experiences with steelfill and brassfill filaments.

Important Stuff to Know

Metal, carbon fiber, and glow-in-the-dark additives will damage normal brass nozzles by wearing the nozzle opening. This can happen fairly quickly so you will want to get a nozzle that is capable of withstanding this wear. Your options include a hardened steel nozzle or an Olsson Ruby Nozzle.

Also keep in mind these filaments are still mostly plastic. The manufacturers are mixing metal and wood fibers into plastic to create a hybrid filament. Typically the non-plastic element is between 5%-30%. Most manufacturers do not list exactly how much. This means you can’t print in brassfill and expect it to be as functional as true brass. In fact it will still be susceptible to all the degrading factors that PLA has. Brass gives no added heat or UV resistance, no added strength, and rarely gives added conductivity.

These specialty filaments require post processing to have any value in many cases. Metal filled filaments will need polishing, tumbling, or aging. Wood filled filaments will look best when sanded and potentially stained.

The exception here is carbon fiber filled filament which provides added stiffness and strength to regular plastic filaments. For the best mechanical properties I would suggest using a tough plastic filled with carbon fiber like NylonX.

In all cases specialty filaments are more expensive than regular filament without the filler. Sometimes significantly more expensive with rare or expensive fillers.

On to the Brassfill and Steelfill

If you read the above you might be wondering what is the point of certain speciality filaments? With the exception of carbon fiber filled filament, most do not offer any beneficial functional properties. It all comes down to the look and feel for me. The metal adds weight to give it a more realistic feel and it also means you can polish, tumble, or sand to make it look like more like a metal object. I printed this statue with brassfill and one with a non-metal filament that is supposed to look like metal:

Brassfill statue
Brassfill statue after 9hrs in the tumbler

PLA statue
PLA statue with metallic color but no real metal

These were both printed at .15 mm but you can see the one that went through the rock tumbler has smoothed out quite a bit more which I think gives the impression it was printed with more detail. Despite both being shiny, the metal fill has that distinctly genuine metallic shininess that you can come close to with plastic, but not quite perfect.

The above metal fill statue was rolled for 9 hours with stainless steel screws (about 600 small screws of varying sizes). This was a suggestion that Adafruit had for finishing metal fill prints.

Because I used steel screws the brass took on a much darker color. To contrast that, I also tumbled another object in 100% brass screws and the difference is significant:

Brassfill object
Brassfill “Hand of the King” model rolled in brass screws

The “Hand of the King” model picked up the polished brass color and added some shiny flakes of brass to the model. You can see during tumbling the sword tip broke off which I expected. I ended up later filing it to a point again and it looks decent.

You can see what the brassfill looks like before using the rock tumbler:

Unpolished brassfill object
“Hand of the King” unpolished

You can see the polishing not only brought some shine to the object but it also, like the previous print, smoothed out the layer lines to give a more detailed look to the print.

I also experimented with steelfill with a House of Stark coin (there is a bit of a Game of Thrones theme going on here):

Steelfill Object

The polishing in the rock tumbler did help smooth it out a bit and added some shine, but overall I’m not as happy with the result. I think a lot more post work would need to be done to achieve a better “stainless” look. Also I found the weight added by the stainless fill provided less of an impact than the brassfill filaments. Considering how expensive the stainless steel filament was I would be reluctant to buy it again.


  • If you are going to roll your objects in a rock tumbler make sure they are sturdy enough to withstand the forces
  • You can make objects even heavier with more infill but at the cost of print time and filament
  • No matter how much cleaning, even with soap and water, I could never get the polished metal objects to completely stop marking up anything they touched (my hands, paper, cloth) – I ended up spraying them with clear coat and now they can be handled without issue
  • If you want that golden brass look make sure you use 100% brass screws and not plated – Even brand-new brass plated screws will turn prints dark grey
  • Filament with metal fill are more brittle and will be more difficult to print on printers that are not using direct-drive extruders
  • Store specialty filaments in an airtight container to avoid oxidation or water absorption in the case of woodfill or corkfill
  • Tumble prints for a minimum of six hours for small objects
  • Don’t expect true metal properties; you are still dealing with a filament that is mostly plastic
  • Use a nozzle that is resistant to wear for filaments that have harder materials
  • You will get strings and blobs with metal filled filament on more complicated objects, but tumbling typically takes care of these for you

3D Printer Safety

If you own or are considering purchasing a 3D printer you should be aware of the potential hazards involved. Please research your printer or the printers you are considering to find out if it has a higher potential for fire and  if there are ways the community has made the printer safer.

Buy a Printer with Safety Features

Your printer should have firmware (software that runs the printer) which has:

  • Hotend and bed thermal runaway check.
  • Minimum temperature check
  • Maximum temperature check

Thermal Runaway: printer is cooling down faster than it should be or not heating fast enough. This check ensures the thermistor (the device that measures temperature), and the hotend (the part that melts the plastic) are performing as expected. If the hotend is being asked to heat to 215 °C but the thermistor is reporting that the temperature is actually going down, there clearly is a problem. Some printers will simply try to heat the hotend more to compensate and this can actually result in a fire.

Max and Min Temp: If the slicer software requests a temperature of 900 °C it will ignore the command. If the printer detects a temperature below expected cold room temperature or something radical like -600 °C – a sign the thermistor is not working. In both cases the printer should stop printing and turn off power to the heat bed and hot end.

Additional Safety Features:

  • Fans spin up to full blast to help prevent the hotend from overheating in the event that the thermistor is incorrectly reporting the temperature or some other temperature related failure has resulted in the hotend attempting to heat up beyond its usable temperature.
  • Printer that detects fans are not working.

Some cheaper printers come with bad wiring, uses wires that are rated for lower than the amperage being sent over them, or has not fully secured wires either in the power supply or on the circuit board running the printer. Check reviews to see if the printer you have or are interested in suffers from this and usually the community will have a solution available.

If you are building the printer from a kit make sure you follow the instructions carefully. This is most important when it comes to wiring the power supply and heat bed. A loose cable can result in a short which can cause a fire if a printer is unable to detect thermal runaway.

Do your research and make sure you are getting a printer that has safety checks enabled and are proven to work.

Fire Alarm

Please buy a fire alarm and put it directly over your printers. The faster you are notified of a catastrophic problem the better chance you have of getting to safety or even saving your property.

Don’t Rely on Fire Suppression Alone

Some people have suggested using a fire suppression system like those found in kitchens. The idea is if a cooking fire gets out of hand the heat will melt a switch that dumps fire suppression powder or foam. This is usually ok for cooking fires because the source of the fire is extinguished (food) and, even with the burner continuing to heat, typically the worst that happens is smoke damage.

I don’t believe this is as useful with 3D Printers because the problem isn’t that the hotend (burner from the example above) is on, but that the hotend is heating well past safe levels due to a printer malfunction. While the initial fire might be suppressed, another one can easily start from molten aluminum reaching other flammable parts on the printer.

Another option is to run your printer in a fireproof or resistant enclosure (steel or concrete). If it is fully enclosed flames would be better contained in the event of a fire.

You should check with your local fire department for expert advice in regards to handling fire like this with a fire suppression system.

Unsupervised 3D Printers in Multi-Unit Homes or Public Buildings

If you are operating your printer in a location where other people’s lives may be at immediate risk in the event of your printer malfunctioning like at a school or apartment building, you should seriously consider never running it unattended.

At a minimum, you should thoroughly test a printer you don’t have experience with to ensure it is reliable and then regularly test to make sure sensors and safety features are working as expected.

Children and Printers

Make sure children are supervised when using a 3D printer. For those of you with small children you should be aware that the hotend on a 3D printer, which melts the plastic, can get up to 300 °C which is 570 °F. This is typically hotter than your electric oven can heat up. The printer bed, if heated, can get up to 90 °C which is 194 °F. Both these temperatures are capable of causing serious burns.

Many printers, especially cheaper ones, do not come with an enclosure. This is to save costs or, in the case of printers primarily used for PLA, to avoid an enclosure heating up too much and negatively affecting print quality. The printers that do have enclosures do not usually have a lock or child safety mechanism.

Particulates and Fumes and Toxic Materials when Printing

This topic isn’t discussed much, but be aware your printer generates invisible, but often smelly, particulates while printing. Some materials are worse than others (ABS compared to PLA). There is not significant research to show printer fumes and particulates are bad for your health, but you might consider using the printer in a room with decent ventilation.

A lot of what has been discussed covers FDM or FFF printers which melt plastic and put it down in layers. Another type of 3D printer that is becoming more popular are SLA printers that use UV cured resin which is toxic before it is cured. You should not touch liquid resin until it has been washed in alcohol and cured in UV light.

Don’t Take My Word For It

Hackaday –  3D Printer Halts and Catches Fire

Hackaday – Don’t Leave 3D Printers Unattended

Thingiverse – Anet A8 almost burned down my house

Punished Props – Avoid a Fire Hazard

Maker’s Muse looks at safety when it comes to SLS printers that use resin:

Maker’s Muse – Resin 3D Printing Safety – Important for Beginners!

Thomas Sanladerer – Everything you need to know to make your 3d printer fireproof!

Thomas Sanladerer – Testing my printers for fire hazards – results all over the place…

More advanced users can modify the firmware on their printers using Marlin to enable safety features:

Thomas Sanladerer – Maker your 3D printer safer: Marlin configuration!

Damaged thermistor reports the wrong temperature and hotend continues to heat until fire in this test. Example of what can happen if your printer does not have thermal runaway protection:

Chris Bate – Hotend thermal runaway test #2

Building the Prusa i3 MK3

My previous experience putting together 3D printer kits has included splicing wire, soldering, adjusting potentiometers, cutting and drilling parts, and even building small circuit boards.

The Prusa i3 MK3 kit suffers from none of the above. It is a well designed kit that I would compare to building a complex lego set. This is helped by a detailed manual (both printed and digital), properly labeled bags, community discussion, videos, and hundreds of hours of testing.

If you are confident you can properly connect negative and positive wires to the correct terminals and follow a visual guide showing you where and how to connect pre-made wires, then recheck everything, I believe this kit isn’t as hard as it might seem on the surface. With a few tips I think most people, who can handle the above, can easily put together the i3 MK3 kit.


  • Expect to spend 4-8 hours building the kit.
  • Always read the instructions first before starting. They often include important build instructions that help you understand why you are performing the tasks.
  • I highly recommend using a torque controlled screw driver designed for electronics/delicate-parts and set it to the lowest torque setting. Allen keys are too easy to over tighten and you can end up with cracked parts. I know this is an added expense, but that tool will come in handy in the future so it is not a lost investment.
  • Before you let loose with the power screw driver or even the Allen keys I would hand start any screws to make sure they catch appropriately. This will prevent binding and stripping of threads.
  • Triple check the power supply and bed wires. One of the few things that cannot be fixed is powering up the printer with it incorrectly wired for power.
  • The P.I.N.D.A. probe should be very close to the surface of the print bed while the nozzle is touching. Setting the P.I.N.D.A. too high will result in the nozzle possibly crashing into the bed. The manual recommends using the thick part of the zip tie, however I used the thiner part of the zip tie instead based on my experience with the P.I.N.D.A. probe on the Prusa i3 Mk2.
  • Use the online manual if the print manual images are not clear. I found this particularly helpful for the E Axis and E Axis wire strain relief.
  • A majority of screws and parts are color coded in the manual. The manual will show, for example, a screw boxed in orange then often an orange arrow or box where the screw goes and finally an orange bullet marking in the text that refers to this part and screw.


Aside from using the occasional wrong screw I did run into two significant issues that you might be able to avoid.

In the right Z part you need to insert a nut into a hard-to-access slot. Unlike other places in the manual where you can essentially pre-seat the nut, this is not possible (see the blue box below).

Right Z nut placement

When trying to insert the screw it ended up binding and I was not able to either reverse the screw or tighten it. The nut would spin and even with significant force trying to hold the screw in place I could not dislodge the two. I did this without the trapezoidal nut installed because I was trying to align the nut and screw. The trapezoidal nut cannot be attached due to the screw head. The solution, for me, was to cut the screw head off:

Z nut fix

The printer works in this setup, however I will print a replacement right Z part to have the trapezoidal nut properly secured.

The second issue I had involved the calibration wizard. I was getting self test error “X-Axis Length” which essentially means the printer is not returning the expected length of the X axis. Often wires or zip ties can cause this, but in my case the Z was misaligned enough that there was minimal binding stopping the X from moving the full distance. To solve this you can exit the setup wizard do a quick Z calibration. Once that was done the self tests all passed in the wizard.

I hope to put up a review of the Prusa i3 MK3 in the next month or so.