Here is my paper-craft Aperture Science Weighted Companion Cube. As I built this, I was also working on another project... A tutorial on how to build one of these MY WAY. My way makes the model tough and heavy, enabling it to last a lifetime and resist a lot of damage. The only downside is that the construction process takes a while and will require patients. But it's all worth it in the end.
Part 1 of Tutorial: [link]