holmes4:
Try using a servo they are small, cheap and require only a single control pin.
Hm, don't they have to share the same power supply as the Arduino? One of my worries is that there'll be too much current drawn from the 9v battery I have powering that, but I'm pretty new to hooking up motors.
PeterH:
In a confined space looking for small forces, I'd have thought a small motor and pulley system was your best bet. It's possible to get absolutely tiny motors, if you're stuck for space. How small a motor you could get away with would depend on the force and speed the motor needs to provide.
Ideally, I'd want to move 2-3 oz about 2-3 inches within, say, about a half second. I plan on making the moving parts as light as possible. However, two of them will be moving at once, and I'd also like them to stay in place if the whole thing is turned upside down.
I do appreciate any guidance, as while I have no problem writing code and dealing with digital logic I'm a complete newbie when it comes to connecting moving parts and I'm (perhaps too) paranoid about blowing something out on my Arduino.