Made the top, corners and bottom separate pieces. The corners are a snug fit as I designed them to be glue free but not loose enough to come apart unintentionally. This gives you the option to swap out photos. You can also make them permanent with a little super glue. Just don't glue the top litho panel so you can slide it out to turn the light on! I used a battery operated LED light puck from Wal-Mart that slides right in to the bottom hole feature.

UPDATE: Included a few designs for the top panel and added photos of a few completed boxes.

OVERHANG SUPPORT: needed for the legs and the top panel. See photo example for recommended support areas.

You get two in a pack for $9.00. >> https://www.walmart.com/ip/GE-LED-Wireless-Puck-Lights-Battery-Operated-Touch-Activated-2-Pack/168006227

Corners can be printed flat without support.

I use Flat Lithophane Maker >> https://lithophanemaker.com/Framed%20Lithophane.html for the litho photo stl generation.

Dimensions for the lithograph side panels are 98mm x 105mm x 3mm. Dimensions for the top panel are 105mm x 110mm x 3mm.