I love this lithophane light box by tjwittkop and made a version as a gift. The only issue I had with it was having to glue the top to the bottom, making it impossible to change out the lithophanes on the sides of the box.

So I designed extended pillars and slots so you can slide the top part onto the bottom part (using FreeCAD). The tolerance is +/- 0.3 mm which prints with a snug fit on my printer (Elegoo Neptune 3 Pro) so the top will stay in place but is still removable to change out the lithophanes. It printed quite well so I thought I would share for anyone else interested.

I also recommend printing the lithophanes with a 90 mm max size for a snug fit (see other settings in images from the original thing).

Print the bottom (body) without supports and the top with supports. I recommend connecting the support lines for the top so they pull out easier.

ELEGOO

ELEGOO NEPTUNE 3 Pro

No

Yes

0.2 mm

15%

Print top part with supports. Body part doesn't need supports. Created and printed lithophanes following settings and instructions from original thing except with 90 mm max size for the lithophanes for a more snug fit.

You may consider verifying the tolerance of your printer/filament by printing a tolerance test first. You want a tight fit while still being able to freely move the parts at the 0.3 mm tolerance range. I used this one to test my printer before designing this model: https://www.thingiverse.com/thing:2301071