I've designed this Lightbox so that the front and the backside will just slide into each other an stay tight. The LED Strip goes onto the backplate which is then to be slided into the front.

The back has a hole for a switch and an USB cable.

Of course you an also just add the LED Strip and push the USB connector through the hole.

Switch: https://www.amazon.de/dp/B08CY41YT5

Cable: https://www.amazon.de/dp/B0CLV9BLML

LED Strip: https://www.amazon.de/dp/B07CGKT9B2

Have fun printing and building this lightbox.