Coin generator — a photo or crest, raised on a 40 mm blank
This page opens on the coin preset: your image becomes a height map on a round 40 mm blank, 2 mm of body with 1 mm of relief on top — the proportions of a real challenge coin. Dark parts of the picture rise, light parts sink, and the whole thing prints flat with no supports.
Model
Turns the whole photo into a raised surface, like a coin or bas-relief.
Relief
Base & mounting
Tips
- Logos and icons trace best from high-contrast black-on-white artwork — drag Threshold until the preview matches the shape you want.
- Photos belong in Relief mode; tracing a photo produces confetti, not a model.
- Keychains: keep the artwork at least 1.5 mm thick and the tag 2–3 mm so the ring hole doesn’t tear.
- Stamps must be mirrored — the preset does it — and print best with the relief 2–3 mm proud of the base.
- Print flat on the bed; a raised logo on a plate needs no supports.
Capabilities
How the blank is built
- A true round blank: the disc is cut from the image, so the coin has a clean circular rim instead of a photo with rounded corners.
- Challenge-coin proportions by default — 40 mm across and 3 mm tall — sized so a batch fits on any 180 mm bed and prints in under an hour each.
- Brightness becomes height across 300 samples on the long edge, roughly 0.13 mm per sample: finer than a 0.4 mm nozzle can reproduce, so the nozzle is the limit, not the picture.
- One switch flips which tones rise, so a light emblem on a dark field comes out raised rather than sunken.
- Turn on the hanging hole and the same blank becomes a medal or pendant, with the hole cut through the disc as part of the solid.
- A single closed mesh, watertight by construction, with the STL size shown before you commit to the download.
Process
How it works
- Choose a strong imageCrests, badges, silhouettes and high-contrast portraits read well on a coin. Busy backgrounds do not — crop tight before you drop the file.
- Set diameter and reliefWidth is the coin diameter; relief depth is how far the darkest tones stand above the blank. Keep the blank at 2 mm so light areas always have material under them.
- Print at fine layersExport the STL and slice it at 0.12 mm or finer, face-up on the bed. A coin is judged in reflected light, and layer height is what you see.
Proportions
What size should a 3D printed coin be?
Circulating coins are small and thin — a two-euro piece is 25.75 mm across and 2.2 mm thick — and a print at that size loses everything but the outline, because a 0.4 mm nozzle cannot draw a face 8 mm tall. Commemorative and challenge coins solve the same problem by being bigger: 40 to 50 mm across and about 3 mm thick. That is what the preset ships, 40 mm and 3 mm, and it is the smallest size where a portrait still reads. If you want something that feels like pocket change, print 30 mm and accept a simple emblem; if you want a display piece, 50 to 60 mm gives the relief room to breathe and still prints in about two hours.
Relief
Why deeper relief makes a worse coin
It is tempting to push relief depth up until the model looks dramatic on screen, but a coin is not lit from behind — it is read by the shadows its own surface casts. Around 0.8 to 1.2 mm of relief on a 40 mm disc gives shadows that are crisp at arm’s length. Past that, the walls between a dark region and its light neighbour approach vertical, print as ragged near-overhangs, and fill with shadow that reads as a black smear rather than detail. Smoothing helps in the other direction: a value of 1 or 2 blurs JPEG noise that would otherwise become a fine crust of bumps across the field, without touching the large forms the eye actually follows.
Notes
Good to know
- The rim is a plain cylinder — reeded, knurled or lettered edges are not generated, and neither is a raised border ring.
- One face is relieved. A double-sided coin means printing two halves and gluing them back to back, or mirroring the second face yourself.
- The disc is cut from the middle of the image at its shorter dimension, so a wide photo loses its sides; crop to a square first if that matters.
- Relief height comes from brightness alone, not from depth in the scene, so a dark shirt in a portrait rises as high as dark hair.
FAQ
Questions, answered
How do I turn a photo into a 3D printed coin?
Drop the photo here and it lands on the coin preset — a round 40 mm blank with the picture raised on it. Adjust diameter, relief depth and smoothing while you watch the preview, then download the STL.
How thick should the coin be?
Two millimetres of blank under one millimetre of relief. The blank matters: it is what stops the lightest parts of the image from thinning to nothing, and it is what keeps a 40 mm disc from curling off the bed.
Can I make a medal or pendant instead?
Yes. Switch on the hanging hole in Base & mounting and a 4 mm hole is cut through the top of the disc as part of the same solid, ready for a ribbon or a jump ring.
Why does my coin look muddy?
Usually too much relief on too little contrast. Lower the relief depth toward 0.8 mm, raise smoothing by one step, and crop the picture so the subject fills the disc — a face that occupies half the coin has half the detail to work with.
Should I paint or polish the coin?
A wash of acrylic wiped back off the raised areas is the fastest way to make relief pop, and metallic PLA takes a light sanding on the high points beautifully. Do not sand before painting: it flattens exactly the edges you want.
Is the picture sent anywhere?
No part of it leaves the tab. The image is decoded to a brightness grid, turned into a mesh and written to an STL entirely in local memory, so a family photo stays on your machine.
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