SquareBox+Top

I've been accumulating numerous small 3D printer parts (primarily hotends, fans, and wiring) and I needed a place to keep them. So I modified the designs of arcbox7 and arcbox8: I made the box square, larger, and changed the design of the top so when printed without supports the inside of the top ends up looking nice.

Doing this was pretty easy since I use parametric design software (http://birkbinnard.com/blog/parametric-modeling/), but it did take a while to get the geometry of the top's ha