Here is a frame I redesigned using the Bambu lithophane design as a template.
I designed the frame to accept the Bambu LED light and also integrated a stand which allows the storage of 3 lithophanes making this a great design to make as a gift.
The 3mf file is designed with the best settings I used to make the frame but it required the use of support filament as a support interface though with careful settings you can make it supporting without support filament.
I printed this with no issues with PLA the photos is PLA silver using Bambu PLA and PLA support from Bambu labs.
I have also included the step file as well if you which to make edits which I will allow but not resale of the frame without my consent.
The photos include the rear which shows the integrated lithophane storage and the front photo shows a white PLA light guide installed.