This was a request I had gotten and I'd never heard of a Lithophane so I looked into it and this is what I came up with! I did most of the legwork in getting the images separated into parts in Paint.net.
Then after that I imported them into Tinkercad, arranged them and layered them at different heights so light would travel through them differently. I made the mistake of printing with a low infill. I would recommend going higher with that.
Image to SVG:
Image to Lithophane:
Watch here: https://youtu.be/jH_rpieYP1U
Printer: Robo3D R1
Filament: Hatchbox Clear PLA
Layer Height: 0.3mm
Infill: 30% (I would recommend higher)