This design is based on the original models from Bambu Lab, which can be found at the URL below.
Original STL files: CMYK Lithophane Printing Guide | Bambu Lab Wiki
Unfortunately the original URL does not contain working 3mf files, so we decided to create this helper project. I hope Bambu Lab won't mind, I try to include all links to their work.
Bambu CMYK LED Backlight Board you can buy here: Bambu CMYK LED Backlight Board | Bambu Lab EU