About this 3D model

An experiment to make a plastic "coil" spring printed in a single piece. The design has concentric cylinders that restrict the movement to mainly vertical and an outer springy part that provides resilience. The more vertical bars, the stiffer the spring. The more horizontal rings, the greater the extent of movement. It's resistant to twisting, but would do very badly in tension I think. Also note that the spring part need not be on the outside of the concentric cylinders: it could be embedded between them, so protected from damage.