Used for drying 4x5 Harman Direct Positive paper for use  with my Pinsta pinhole camera. They also make nice fridge frames.

Print in PLA 15% infill .

I used 10x3mm black magnets. I have included the .step file to modify to the magnet size you have on hand.

10x3mm Magnets I used,

afflink: https://amzn.to/3q0trIl