here's my solution (3 lines), very fun puzzle! i know 2 lines is possible with this method, but i think i would need to rethink it completely for 1
ooh thats a fun solution! i like how it gets the desired sequence within a repeating [13212] loop, wow! (or would, if the momentum was conserved in the physics engine)
i really like how simple and open ended it is, yet still pretty tough