Read about the OpenFlexure Microscope in the current issue of MagPi today. Thought this would make an excellent candidate project for the P2. Also, the stepper motors they use, the 28BYJ-48, are actually a MIKROE-1530.
Ken, any chance Parallax could stock these since you have a new partnership with them? DigiKey has 81 for $8.32/ea and Mouser sells them for $8 but doesn't have any in stock. I think this microscope might be my next project.