Moved the cover spool down to flush with the drive spool.

Went from using a pushrod to a pull, which I'm much happier about.

Changed from a binder clip to a pen spring, and it's now on the drive pulley ratchet instead.
Tweaked the gear ratios and ratchet positions so each lever push locks at the next ratchet position at 2/3rds throw, so anything more than 2/3rds is still one advancement.

Added servo support.  You should be able to run two of these with one servo.
Maintained the ability to change the cover spool direction in code, and you only need to reprint 2 parts.
I settled on 12mm width.  It was a lot easier to make it strong enough supported from one side that way.  If you are stacking them, you can go back to 11.5 or even 11mm.

Source has been updated.

Printing again...