3D Print a Face for Your Robot: Free Files, Honest Instructions

There is a growing pile of "robot head" files on the model marketplaces, and most of them are sculptures. They look good on a shelf. They do not fit an actual robot, because they were never measured against one. This page is about the other kind of file: a mask shell cut for a specific humanoid head revision, with the sensor openings where the sensors actually are, that you can download free and print this weekend.

These are workshop notes, not a pitch. We will tell you what the file is, why it costs nothing, which filament to buy, the settings that worked on our printers, and the two prints we ruined getting there.

What you're actually downloading

A Botswear print file is not a generic face blob scaled to look about right. It starts in the Mask Lab: you describe the face you want, upload a photo of your robot, and the AI renders the design on your exact machine so you can see it before anything gets made. You get two edit rounds to fix what bothers you. Most people use the first round on the eyes.

When you settle on a design, the file itself is parametric. It is an OpenSCAD model compiled to STL live in your browser (openscad-wasm doing the work; nothing uploads to a render farm), cut for your robot's specific head revision. You can download both the .stl for slicing and the .scad source if you want to change the parameters yourself. Nobody is stopping you. It is your robot.

Every shell includes:

• Eye apertures aligned to the camera positions for that head revision, so the robot sees through the face rather than around it
• Vent slots over the thermal exhaust paths, because a robot head is a computer and computers dislike blankets
• Strap slots for a soft mount, plus a magnetic perimeter mount if you prefer no straps at all
• A total printed weight under 180 grams, which matters more than it sounds; neck actuators have torque budgets and warranty terms

If you want the longer argument for why a face is worth putting on a robot at all, we wrote it up separately in Should Your Robot Have a Face? This page assumes you have already decided yes.

Why the files are free

Fair question, and the answer is not a trick. The print files are free during the beta, which we call Run 001. The business is the stitched version: the same face made in knit textile, machine-stitched, for $99 by reservation. Some people will print the shell and stop there, and that is a fine outcome. Some will print it, live with it for two weeks, and decide they want the soft one. The print file is how you find out which person you are without spending anything.

We would rather state that plainly than pretend the free file is an act of charity. You own a printer. You can smell a funnel a mile away. This is a funnel with a genuinely useful free layer, which is the only kind worth building.

Choosing a material: PLA, PETG, or TPU

The shell is designed to print in PETG or TPU at 0.2mm layers. Here is the honest breakdown, including the material we don't recommend.

PLA: fine for a test fit, wrong for daily wear

PLA prints easily and looks crisp, and if you just want to check fit before committing better filament, go ahead. But PLA is brittle, and it starts to soften around 60°C. A mask sitting over vent slots on a warm head, or a robot parked near a sunny window, will eventually reward you with a warped face. Warped faces are their own genre of unsettling; we cover the psychology in Why Humanoid Robots Look Creepy.

PETG: the sensible default

PETG is the middle child of filaments: tougher than PLA, far easier than ABS, comfortable with heat well past anything a robot head produces. It prints at 230 to 250°C with a 70 to 80°C bed, handles fine at normal speeds, and its main vices are stringing and sticking too enthusiastically to smooth build plates. Use a textured plate or a release layer. If you want one spool and no drama, buy PETG. All3DP has a fuller PETG vs TPU comparison if you want the material science.

TPU: fabric's stubborn cousin

TPU is a flexible filament, and a TPU shell behaves less like armor and more like a very disciplined piece of felt. It flexes with the strap mount, absorbs the small knocks of a machine that walks into door frames, and feels closer in spirit to the stitched knit version. It is also slower and fussier to print. Softness is measured in Shore hardness; 95A is the easy end, and anything softer than 90A will fight a Bowden extruder for its life. Direct-drive extruders handle TPU much better. If you have never printed flexible filament, Prusa's guide to printing flexibles is the best twenty minutes you can spend before opening the spool bag.

Print settings that worked for us

Real numbers from our own printers, plus the failures, because a settings list without failures is marketing.

• Layer height: 0.2mm for both materials. The shell is modeled for it. We tried 0.28mm to save time and the eye aperture edges came out visibly stepped, which reads as exactly the cheapness it is.
• Orientation: face down on a textured plate, concave side up. No supports needed in this orientation for most designs; the slicer will offer them, decline politely.
• PETG: 240°C nozzle, 75°C bed, 40 to 60 mm/s, fan around 50%. Textured plate or glue stick as a release agent, or you risk taking a divot out of a smooth PEI sheet.
• TPU: around 230°C, 20 to 30 mm/s, retraction near zero, part cooling fan off or minimal. Slow is not a suggestion. Our first TPU attempt at 50 mm/s ended as a bird's nest around the extruder gear inside twenty minutes.
• If your design does need supports in TPU: set the support Z contact distance to at least 0.3mm. TPU layers bond to each other so well that supports otherwise become a permanent feature.
• Dry your filament. TPU especially drinks moisture. A spool that has sat open for a month will hiss, string, and produce a surface like a stale croissant. Two failures in, we bought a dryer.

Total print time runs three to six hours depending on material and design. One spool covers several masks, so a failed first attempt costs you an evening, not the project.

Fitting it without blocking a single sensor

This is the one rule: nothing you put on a robot's head may cost it perception. The eye apertures in the file are not styling, they are field-of-view cutouts matched to the camera placement of your head revision, with margin. The vent slots sit over the actual exhaust paths. This is why the Mask Lab asks which robot you have and why the file is compiled per revision rather than offered as one universal STL. A face that fits an Optimus head does not fit a G1, and a file that claims to fit both fits neither.

Mounting: thread a soft strap through the strap slots, or use the magnetic perimeter mount if you want the mask to come off with one hand and no fiddling. Check the fit at the edges after installation. If any aperture edge shows in the robot's camera feed, reseat before adjusting; in our testing, misalignment was a seating problem, not a file problem, every time but once. That once was our bug, and we fixed the parameter.

Print it, or have it stitched

The honest side-by-side. A printed shell is rigid, precise, costs you a few dollars of filament, and you can have it on the robot tomorrow. It is also unmistakably plastic: it reflects light like plastic, sounds like plastic when tapped, and sits on the head rather than settling onto it.

The stitched knit version is the same design in textile: soft, matte, quiet, and it drapes over the contours instead of hovering above them. Materials that read as fabric skip most of the uncanny problems that hard shells can only minimize. That one is $99, by reservation, made per order. We are not going to tell you the print is just as good, because if we believed that we would not have built a knitting operation. Print first, decide later. The file is free for all of Run 001, and once you have downloaded it, it is yours.

Post your result

The best part of Run 001 has been watching what people actually print. The gallery is the show-and-tell: first attempts, material experiments, one memorable mask printed in glow-in-the-dark PETG that its owner now slightly regrets at 3am. Post yours, including the failures. Especially the failures; someone else's spool is depending on it.

Start in the Mask Lab: describe the face, see it rendered on your robot, take your two edit rounds, and download the .scad and .stl. Free while the beta lasts.