Lithophane generator
A lithophane is a picture printed as thickness. Hold it up to a light and the thin parts glow, the thick parts stay dark, and the photograph appears. Drop one in here and you get a printable model with the thicknesses already set to values that work, which you can see and change before you download.
Your photograph is read on your own computer and never uploaded. Family photos are most of what this tool is used for, which is a good reason for there to be no server involved at all.
How a lithophane actually works
Light passing through plastic is absorbed as it goes. Twice the thickness does not block twice the light — it blocks far more than twice, because the loss compounds with every millimetre. That steep relationship is the whole trick: a difference of two millimetres in thickness becomes the difference between white and black when you put a lamp behind it.
So the picture is turned upside down before it becomes a surface. The dark parts of your photograph become the thick parts of the model, because thick material is what stops the light. That is the opposite of a relief, where the bright parts stand up, and it is why this is its own tool rather than a switch on the other one.
It also means a lithophane looks like almost nothing with the light off. A flat grey slab with a faint texture is the correct result, and the picture only exists when there is something bright behind it.
The two numbers that decide everything
The thinnest part is set to 0.8 mm and the thickest to 3.2 mm, and neither is arbitrary. 0.8 mm is two passes of a 0.4 mm nozzle, which is the thinnest wall that prints reliably and the thinnest that stays flat rather than warping. Below it you get gaps, and a gap is a hole rather than a highlight.
3.2 mm is where white PLA has gone as dark as it usefully goes. Past that you are adding plastic and print time for no more contrast, and the shadows start to look muddy rather than black.
Those defaults suit white PLA, which is what almost every lithophane is printed in. For a darker or more opaque filament, reduce the thickest setting — 2.6 or 2.8 — or the whole picture crushes to black. For a translucent natural PLA, you can go a little further.
Flat or curved
A curved lithophane is better in three separate ways, and the setting is there for all of them. It stands up on a shelf without a frame or a stand. It is far stiffer across its width, so a thin panel does not bow as it cools. And a single bulb behind a curve lights the edges about as brightly as the middle, where a flat panel is always brightest in the centre.
Somewhere between 60 and 120 degrees of arc is the usual choice. The width is measured along the curve rather than across the gap, so the picture is never stretched — turning up the curve makes the piece occupy less space without making the image smaller.
A curved one also prints standing on its edge with no supports and no brim problems, which is the orientation you want anyway.
Printing it, which is where most of them go wrong
**Print it standing up, vertically**, with the picture facing the front. This is the single most important setting. Printed flat, every layer line runs across the image and the light picks out each one; printed upright, the layers run along the thickness and disappear. It also means no supports and no overhangs.
**Use 100 per cent infill.** Any gap inside is an air pocket, and air passes light quite differently from plastic, so partial infill shows up as a pattern straight through your photograph.
**Use a fine layer height**, 0.1 mm or less. The layer height is the vertical resolution of your picture, so 0.2 mm halves the detail in one direction.
**Slow down**, to something like 30 mm/s. A thin upright panel wobbles at speed and the surface quality is the whole product here.
A lithophane is a slow print — several hours for a postcard-sized one — because it is small, solid and finely sliced. That is normal and there is no setting that fixes it.
Choosing a photograph
High contrast, one clear subject, and a plain background. Faces work beautifully when they are lit from the front and fill the frame. Group photographs almost never work, because each face ends up a few millimetres across and there is no detail left in one.
Avoid anything dark overall — a night scene has almost no thin parts, so almost no light gets through and you get a dark rectangle. Avoid anything very bright and flat, which gives you a pale one. Something with a full range from black to white is what you want.
Increasing the contrast in any photo editor before you bring the picture here is the single best thing you can do to the image, and it is worth doing even when the photo already looks good on screen.
The next question
Questions
- What thickness should a lithophane be?
- 0.8 mm at the thinnest and around 3.2 mm at the thickest, for white PLA. That is what this page starts with. Thinner than 0.8 and the print has gaps; thicker than about 3.2 and you are adding time for no extra contrast.
- How do I print it?
- Standing upright with the picture facing front, 100 per cent infill, 0.1 mm layers or finer, and slowly. Printed flat on the bed the layer lines cross the image and ruin it, which is the commonest mistake.
- What filament should I use?
- White PLA, almost always. It diffuses light evenly and the standard thicknesses are worked out for it. Natural or translucent PLA works with a slightly thicker maximum. Avoid anything dark, metallic or glittery — the particles block light unevenly.
- Why does mine look blank?
- Either there is no light behind it, in which case that is correct and it is meant to be lit from behind, or the photograph had too little contrast. Raise the contrast in an image editor and try again.
- Should I make it curved?
- If it is going to stand on a shelf with a light behind it, yes. A curve makes it stand up on its own, stops a thin panel bowing, and lights far more evenly from a single bulb. 60 to 120 degrees is the usual range.
- Is my photo uploaded anywhere?
- No. The picture is read by your browser and the model is built on your own computer. Nothing is sent to a server, and there is no account.