I'm always on the look out for surplus items that are mechanical and related to model railroading. Two such items are gears and motors. They can be used for animation and so forth.

I found out a while ago that the spin tooth brushes have a 3 volt motor and a set of gears. They usually get corroded battery contacts or the switch breaks in them, but the motor and gear set is still good.  The gears are called crown gear and crown pinion. They transmit motion through 90 degrees. Plus they have an eccentric with an arm on it. Much like a steam engines connection from piston to the drive wheel.

Picture of one that has been disassembled and one needing to be de-constructed.

Remove the four screws to get the motor off.

And this is what you're left with.

Now all you need is a project to use it in.

Bernd