Rigid Chain Screw Actuator

When researching various printable linear motion technologies, I came across the idea of a rigid chain actuator (https://en.wikipedia.org/wiki/Rigid_chain_actuator) and decided to create my own design based on the Tsubaki Zip Chain Lifter (http://tsubakimoto.com/materials-handling/high-speed-lifter/zip-chain-lifter/) by simplifying the zipping action and replacing the sprocket drive with a screw drive.

This thing is the result: a screw of theoretically unlimited length, which can assemble and disassemble itself as necessary. I envisioned this, when combined with something to constrain the motion, such as a Sarrus Linkage, as a very printable Z platform lifter for 3D printers. So far this is just a technology demonstrator, but I wanted to share this since it's a pretty cool mechanism in my opinion.

The design is fully parametric and the OpenSCAD sources are in sources.zip file.

The input shaft is compatible with standard 6.35 mm hex bit drivers. The input shaft is designed to b