Everyones favorite Weighted Compainon Cube from the Game Portal, hollowed out to store your stuff or to put a gift in,
to give to your favorite test subject.
Print 2 of both the CCube top.stl and CCube side.stl and glue them together..
Print 4 of the CCube wall.stl
they can be glued together at the edges, glued to the bottom lid or both,
the walls will hold together on their own when the box is closed
(though it may collapse if not glued together when picked up by the walls)
I recommend .20mm layer hight. and around 15% infill.
it all prints without support.
If you would rather not deal with gluing the lid pieces together, you can try printing 2 of the CCubelid.stl with raft and full support. (though I do not recommend this)