Mk 12. (partial reconstruction of ~). First of the "X-wings". Uses one rubber band across top of arms and bits of foam to allow flush contact.
Mk 13. Much shorter cross-arms.
Mk 14. ran for 36 hrs (before motor failure)
Mk 15. BIG motors, geared down 1:3 twice (ie 1:9) - still runs hillariously fast. Simpler contact arms though... first of the "Y-wings"
Mk 15 gears
Mk 16. Micros geared down 1:3.
Mk 16. gears
Mk17. belt drive 2:1, narrow wheels
other side of 17.
some Mk18s clustering in the pen (kind of :)
doing something else (all right, they're not doing anything really)