Box with lid
by randrews, published
This is a box with a hinged lid, large enough to hold various small things, like maybe cards. It uses a straightened-out paperclip for the hinge pin, and can be held closed with another paperclip.
Print it out, I used 10% infill and it came out fine. You'll probably need to drill the holes out a bit to be able to work the paperclip through, but it should be very snug once it's in. Get a second paperclip and use pliers to turn one end into a loop, then use through the holes on the other end to hold it closed.
Here's the model on Tinkercad: