I just discovered 507 movements, what a great resource! Back in my active Halloween days, I used to spend a lot of time figuring out how to turn simple rotary motion (as available from a myriad cheap motors) into some form of erratic or lateral motion. Or lateral motion (as available from a pneumatic piston) into some other form of motion. I have the 4 volume set of Ingenious Mechanisms, which is even more excellent. But the 507 site is free!