If you like to tinker with motors you'll find that a lot of motors from toys and equipment have stubborn pinion gears stuck on the shafts. These can be a pain to remove, and while prying on them or punching them out with a hammer can sometimes work, you risk damaging the motor.
This will show you how to make a very effective gear puller with basic tools and next to no cost.
Step 1: Cutting the frame
I used a piece of 1" square steel tubing with 0.1" wall thickness. I cut it to a length of 0.75" with a hacksaw, it doesn't have to be pretty.