Here is a lithophane box I designed. I was going for a classy grandpiano-ish sort of shape. I made it as a gift for my grandparents. My grandmother is blind and thought maybe she could "feel" our wedding pictures.
It fills up a prusa's print bed so your printer needs to have at least 200ish mm wide. For best results I recommend woodfill pla that is sanded, stained and then coated with urethane. Use whatever you think looks best for color and follow the manufacturers instructions. The notches on the frame sides are a bit week, they were intended to be used with super glue so if one breaks no worries, just align it when glueing.
Supports are only needed for the bridging at the back of the walls STL. You could try it without. Print the base without supports.
The dimensions of the lithophane needed for this box are: 200(L)x133.3(H)x3(W).
The light socket I used is this one: https://smile.amazon.com/gp/product/B01IEE57EM/ref=ppx_yo_dt_b_asin_title_o07__o00_s00?ie=UTF8&psc=1
I used a fairly low power led light bulb and it didn't melt. I would not recommend a high wattage incandescent bulb.
Happy printing. Let me know if you have any questions! Cheers.