1. Have a fatter wallet
2. Have a greater sense of accomplishment
3. Sand (among other tasks) the hell out of things!
The Rotary tool I'm showing you how to make will have interchangeable tips for it (though I'm only showing you how to make a sander), light weight, and a LOT more fun than a store bought tool could ever be, unless that store bought tool involved lasers, sharks, and spinning blades...but thats for another time.
Before we start: Be careful, nothing here is too dangerous, but they can make you uncomfortable. You could get shocked by the battery since our switch is so "DIY" (Don't use this with higher voltages) though it will just tingle, not injure you. The aluminum can will be sharp when you cut it. So don't rub the sides of it..duh. And of course using a blade of any kind can always be dangerous. Just use common sense, people.
Step 1: Supplies
You will need:
1 Cheap toy that has a motor. (Mine is part of a small train from the dollar store. My dog ate the track, leaving me free to think of a use for the motor) For a toy, check the dollar store, or, after a holiday, CVS puts all of its holiday themed stuff on a 75% off sale. You might as well get a $3-5 hobby motor from radio shack if you're going to go buy one though, they will be more powerful.
1 Aluminum can
A small amount of sand paper
Wire (your toy may have some that you can scavenge)
Something to cut with
Glue ( I used hot glue)
Possibly pliers to make thing fit how you want them to
A small amount of aluminum foil.
It may seem like a lot, but things like the battery, motor, and wire can all come from one source.