Non metallic possibilities are interesting since adding complexity to a plastic part is essentially ‘free’… as long as you can remove it from the mold. Here’s a concept for locking the panels together on the inside with metal rods. Depending on the design this could mean the sphere’s could be constructed incredibly quickly since each edge only requires pushing a rod into place rather than bolting panels together.

Of course there are a lot of other considerations, such as strength, weight, safety and cost but this is an interesting concept.

Screenshot 2014-12-02 20.03.10