Summary

These are different versions of a four arm screw-box.

I was inspired by the following design to make this one with the measures I need.
http://www.thingiverse.com/thing:582221

I have designed it mainly to contain an alto saxophone mouthpiece I printed (there are different models of it here in Thingiverse), but it can also contain any other kind of thing.

Edit: In the first version (1.1) was quite difficult to separate both parts so I've extended the base. I recommend to print the box B and C as it's easier to make them fit.

Edit 2: I created a new version of Box C with supports. As the piece was being printed it vibrate too much and it printed it wrong. After printing it, you'll just have to cut the support and smooth the surfaces a little bit.

I recommend printing version "Box B1.2" and "Box C 1.3 with support".