A collection of solutions for Fantastic Contraption:
Tube - a minimal tube crawler.
U-Turn - a floppy, crawling chariot.
U-Turn (again)) - a simple cart which uses leverage to apply force on the ceiling.
Back and Forth - an awful contraption.
Back and Forth - a better version which uses many wheels for low friction, and no bridge.
Higher - a ridiculously simple stick-flicker.
Around the Bend - a tiny triangle that flops to change direction.
Solutions by Others Which I Like:
Back and Forth - brilliantly simple because of it's use of rotation reversal.
Four Balls - reciprocating machinery.
Four Balls - multi-stage machinery.
Spinner - just a fast-spinning construct.
Glitching Spinner - a spinner experiment that glitches and goes horribly wrong.
Glitching Star - six glitching spinners, all tied together.
Super Glitching Star - a much more rigid version of the glitching star. Explodes into the finish.
Bizarre Spinner - a Mars mission that accelerates bizarrely.