HOWTO: Organic, erratic gears

Here's a mesmerizing three-minute tutorial on cutting erratic "organic" gears that spin freely despite their odd shapes. After watching it, I was left wondering how you'd make a third (and fourth, and fifth) gear that could mesh with the system without repeating the earlier gear forms, to create an enormous, improbable Rube Goldberg display.

How-To: Make Organically-Shaped Gears