I've been experimenting. Finding different ways of folding a cube flat so that it can spring up again. I have a few different projects planned with fold flat shapes at their centre.

There is a downloadable file at the end of this post so if you are a member you can try this at home. This shape works nicely. Two tubes at ninety degrees to each other. The inner tube is 1/2mm shorter on each side than the outer one so that they fit together snuggly.

The finished cube is nice! There are no obvious creases and edges. Once popped up it really is hard to see that it folds flat! I just need to work out where to fit an elastic band.

This is the cube made from the cross shaped net in the download file. A single diagonal crease on opposite faces allows the model to fold flat. It works well but the gap round the edge of the face is kinda big and ugly.

This one works well. It folds flat and pops up nicely. The half faces work as a natural limit to the movement of the model.

I'm going to have a go at elasticating the first model. I might have a go with other shapes as well perhaps a pop up dodecahedron next!