I made a box with a slot in it, and a hole in the bottom to take a rotating USB adaptor.
The box is in two parts, the main body and a thin piece to go on top to create the slot.
It was easier to print that way, otherwise you'd need supports for the gap.
I carefully superglued the two parts together, making sure I didn't get glue onto the inside of the slot.
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I had the USB adaptor, a round power bank and a 6 LED USB stick to hand,
so I used those to light the lithophane.
I've included a box without the hole so you can fit a battery and LEDs inside if you wish for a cleaner look (I just used what I had in my parts box).
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USB Adaptor:
https://www.ebay.co.uk/sch/i.html?_from=R40&_nkw=New+USB+2.0+Male+To+USB+Female+360+Degree+Rotation+Angle+Extension+Adapter&_sacat=0
The author marked this model as their own original creation.