Physics : handywork

In the exercises class of my Crystallography course, an assignment was given :

Craft a cube and bring it to class next week. It can be made of any material. You will need it to help you with the exercises.

So I cut a cube out of some insulation foam. But I'm not completely pleased with the result.
First I thought of making a cube from cardboard, by drawing some squares, cutting them from the cardboard and folding them together. But I figured this cardboard cube would be crushed when transported in my backpack, so I needed some structure that's not hollow.
Insulation foam is very light and relativily easy to sculpt, so I chose this material and started creating my cube, by measuring, cutting and sculpting. The end result looks like a cube, but not all sides are completely square. But it will do for the exercises.

This course starts to become some sort of handywork class, as in a few weeks we will be instructed to grow a crystal at home, starting from a beaker containing a dissolved substance. It's all very exciting. :-)