bit

most recent versions of all logics so far are at https://www.thingiverse.com/thing:2829196
I recommend downloading from there.
this is a single bit memory gate created using just links and pivot points based on the papers linked below.

the scad file is in the parent thing 4 bit register

http://nextbigfuture.com/2016/04/molecular-mechanical-computer-design.html

http://www.imm.org/Reports/rep046.pdf