Capsela! THANK YOU! I've been googling "little plastic bubbles with gears in them" occasionally for years without finding these.

Between this, K'nex and the original Macintosh my life as a programmer was more a destiny and less a choice :P

Edit: Holy shit, when I google "little plastic bubbles with gears in them", Capsela comes up. Maybe google has gotten better at vague searches in the last decade :P