Thumb bolt - M24x3

Thumb bolt is made to basically test the [Thumb screw](http://www.thingiverse.com/thing:999626).

Longer versions available if someone requests one.

Other compatible things:
- [Screw](http://www.thingiverse.com/thing:999626)
- [Tightener / Thread tool](http://www.thingiverse.com/thing:999629)

## Changes

- v2 includes a bolt that works with the tightener tool too.