The model I sold most so far is a simple 6-strut icosahedron with elastic string. It can collapse entirely and bounces back fiercely afterwards. The cord is much more durable than rubber bands, my favorite product tester is my neighbour's son, who hasn't manage to destroy his toy for more than half a year now.
The bamboo sticks I used have a diameter of 5mm, with a 1mm wide groove at either end. The elastic cord has a diameter of 0.8mm, the knot prevents the string from sliding out of the groove, especially once the model is fully assembled. The tension level can be increased by looping the cord more than once, but unless you will do with all connections the symmetry can be compromised.