I wanted to make something that had a lot of power. So I made this. Four motors, two per worm gear (20:1 ratio), both of those worm gears tied to a single axle driving worm gears (20:1 again) that drive the wheels.
It doesn't move fast, but virtually nothing stops those wheels from moving.
But when something does, the worm gears and the plastic axles can store up a tremendous amount of force. Then it explodes. And it breaks my Legos.