peristaltic pump stackable

Designed in tinkercad, purposed to be able to stack several together.
Driven by a single source, but able to individually couple each or any of them to the driive, with an additional reduction of 5:1.
Added mounting holes for 8mm shafts. It might need some spacers in practice.

The concept is to add some cheap lock actuators to engage the gear to the drive, and a spring to keep them uncoupled when non-energized.

I've included in the files a key to join the gear with the head, and a "too