Metal Z's from compound helical arrangements

A 3-ply of 3-plies. In each turn of the superhelix, each component 3-ply completes two turns. Ordinary rope lay is used: the superhelix has twist opposite to that of the three component plies.

The winding-on/winding-off action of Z's requires a wire that can bend around a radius 25x its diameter without permanent deformation. Polymers like ABS can just manage this, but the best spring wire would need to be improved by factor of about two to accomplish this feat.

An alternative for metal Z's is to use wire rope in place of the solid strands. The configuration above naturally locks together when the superhelix is twisted oppositely to the three 3-ply components.

Another possibility is a 3-ply of 2-plies, also ordinary lay.

A 3-ply of 2-plies. Components complete 2 turns in one turn of superhelix.