You may have seen this mechanism already in the "notes" sub-website. I thought it would be worth trying to convert the plywood model into card. Turns out it works just as well!
I'm not sure what the mechanism is called, I'm going with meshed gears for now but would appreciate the actual name from anyone in the know.
This works in the same way as a bevel gear but is far simpler to make.
Here's the finished prototype in its rather neat box. Assembly photographs next.