Use the free tool below: it runs entirely in your browser, and nothing is uploaded to any server.
A lithophane is a thin 3D printed panel that shows a picture when light shines through it. Thick parts block the light and look dark, while thin parts let light pass and look bright. The result is a photo you can hold in your hand, and it looks best in front of a window or a small lamp. This free tool turns any photo into a lithophane STL file that you can print on an ordinary 3D printer. You do not need any design software, and you do not need to create an account.
Using the tool is simple. Choose a photo from your device, set the print width you want, and choose the detail level. The tool reads the photo in your browser, turns it into a height map, and builds the STL file for you. Then you download the file and open it in your slicer, just like any other model. Nothing is uploaded to a server at any point, so your photos stay private on your own device.
Good photos make good lithophanes. Portraits with a clear subject and a simple background work best. High contrast helps, because the whole effect comes from differences in thickness. A busy background with many small details can turn into noise, so crop tight around the subject before you start. Black and white thinking helps too: imagine the photo in grey tones, and ask whether the face or the subject still stands out.
The tool maps brightness to thickness. Bright areas become thin, at about 0.8 millimetres, and dark areas become thick, at about 3.0 millimetres. That range suits most printers and gives a clear picture without a very long print. The print width you choose sets the overall size, and the height follows the shape of your photo. A width of 100 millimetres is a good first try for a portrait.
Detail is a trade off. More pixels across the image give a sharper picture, but they also make a larger STL file and a longer slicing time. One hundred pixels across is a good balance for most photos. If your print looks blocky, raise the detail. If your slicer struggles with the file size, lower it. There is no benefit in going far beyond what your printer nozzle can actually show.
In your slicer, print the lithophane standing upright, not flat on the bed. Standing it up lets the printer build the thin layers cleanly and keeps the picture sharp. Use a layer height of 0.12 to 0.2 millimetres, white or natural filament, and 100 percent infill so light passes evenly. Turn off supports if your printer can bridge the top edge, and print slowly for the best surface. A brim can help a tall thin panel stay stuck to the bed.
Check the preview before you print. The grey preview in the tool shows the height map your STL is built from. If the subject is hard to see there, it will be hard to see in the print too. Try a different crop, or raise the contrast of the photo in any photo editor first. Small changes at this stage save hours of failed printing later.
This tool has honest limits. It cannot add detail that is not in your photo, and it cannot fix a blurry or very dark picture. Very small text in a photo will not read well as a lithophane. The STL is a simple height map, not a sculpted relief, so it suits photos and portraits far better than logos with flat colours. Within those limits, it is a fast way to turn a favourite photo into a gift or a keepsake.
Try it with a family portrait, a pet photo, or a holiday picture. Print one, hold it up to a lamp, and you will see the photo appear. If you like the result, try a larger width or a higher detail setting for your next print. The tool is free, it runs fully in your browser, and your images are never uploaded anywhere.
Before your first real print, run the sample gradient through the tool and slice it. The gradient print shows you exactly how your printer handles the full thickness range, from the thinnest bright section to the thickest dark section, and it costs only a few grams of filament. If the thin end breaks or the thick end looks rough, adjust your temperature, cooling, and speed before you commit to a portrait. This small rehearsal also confirms that your slicer reads the STL correctly, that the model sits the right way up, and that your chosen width fits your build plate. Many beginners skip this step and discover a settings problem four hours into a portrait print, when the only fix is to start again. A ten minute gradient test is the cheapest insurance in 3D printing, and it teaches you what a good lithophane surface should look like before sentiment is involved.