Lithophane generator: turn a photo into a printable thickness map

A lithophane is a translucent panel whose thickness varies with image brightness. Bright areas are thin and let more light through; dark areas are thick and block it. That is the opposite of a depth map of a scene, where brightness represents distance. The same grayscale image can drive both, but the physical meaning is different.

This matters because a depth model is not required for a lithophane. If the source is already a photograph and the goal is a thickness map of that photograph, the brightness fallback is the honest starting point. A depth estimate can add a relief-like sense of form, but it also changes the image into an interpretation of the scene.

The minimum thickness controls how much light passes through the brightest area. Too thin and the print becomes fragile or lets the light source show through unevenly. Too thick and the bright areas turn gray. The maximum thickness controls the darkest area; too thick and the print becomes heavy and slow, too thin and the dark areas lose separation.

The right range depends on the material, the nozzle, the layer height, and the light source. Start with a small test tile that contains a bright patch, a dark patch, and a midtone. Print it at the final layer height and backlight it. Adjust the range based on the tile, not on a screen preview.

A lithophane is usually printed vertically so the layer lines run across the thickness and the light diffuses through them. That orientation also makes the base and the first layers important: a narrow panel can wobble, so a brim or a stable base helps. Print a small version first if the panel is tall.

Layer height affects the number of thickness levels the print can represent. A 0.2 mm layer height cannot reproduce a 0.1 mm thickness difference. If the image has fine tonal transitions, a smaller layer height or a different orientation may be needed. The same logic applies to nozzle diameter: a 0.4 mm nozzle cannot print a wall thinner than its own extrusion.

Decide whether bright means thin or thick. For a standard backlit lithophane, bright areas are thin. If the image is inverted, the result is a negative. Check the first test tile before printing the full panel. Crop distractions, avoid hard shadows, and keep the subject contrast within the range the material can reproduce.

A photograph with a bright background and a dark subject can be difficult because the background wants to be very thin while the subject wants to be thick. Flatten the background or choose a source with a more even tonal distribution. The free workbench lets you adjust the range before exporting the mesh.

The lithophane workflow needs a closed mesh with a flat back, a variable front, and enough base to hold the panel. It does not need hidden geometry or a full object reconstruction. A relief mesh is the right shape of answer: the front surface carries the thickness map, the walls close the panel, and the base gives the print something to hold.

The free preview STL is a low-resolution check for scale and orientation. The production bundle adds a denser watertight mesh and a manifest. For a lithophane, the final test is always the print and the light, not the mesh viewer.

Backlight the test tile with the light source you plan to use. A phone flashlight, an LED strip, and a window produce very different results. Check the brightest area for blowout, the darkest area for lost detail, and the midtones for banding. If the tile fails, adjust thickness or layer height before printing the full panel.

Record the material, nozzle, layer height, thickness range, orientation, and light source. That record is what makes the second lithophane easier than the first. Label the frame and the lamp too, because a different light source can change the result without any change to the mesh.

View the tile at the distance the finished piece will be seen. A lithophane that looks detailed under a phone at ten centimeters can turn into a gray rectangle on a wall two meters away. Use a diffuse light source larger than the panel, because a bare point source creates hot spots that hide the midtones. If the panel will sit in a frame, test with the frame's inner opening and final backing, since both change how much light reaches the edges.