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.
Step 2: Disassemble
WARNING: POPSICLES CAN CAUSE SEVERE BRAIN FREEZE IF EATEN TOO QUICKLY :P
That is probably the most dangerous step. (>'.')>
Take apart the toy, finding the motor and battery, and if you want to use it (the easiest way) the battery dock. Also scavenge for anything else you may want from the toy (LEDs, speakers, fabric, other motors....)
Step 3: Attach the Motor and Wires
You can also attach the battery dock during this step, just tape it on.
Step 4: The Switch
This is where aluminum foil REALLY comes in handy. You need to rig it so that you can put the wire somewhere touching the battery contact and have it stay, but then move it to turn off the Dremel. For me, this was around the back where some metal came out. I pinched it over the foil. The foil was then rolled over so it could hold the wire. It may be different for you though.
Step 5: The Tips
1. The same length as the motors gear circumference
2. A bit wider than the gears hight.
I know, pretty strict, right?
Now roll the metal around the gear, and glue the ends together, so its a cylinder without bases.
Next, cut out a piece of sand paper, with the same length as the piece of can, and the same hight as the gear. Glue this onto the cylinder.
Once all this dries, slip it onto the gear, and crimp it in a little so it stays on better. Fortunately, these are easy to make, so once your sand paper wears out, you can just make a new one. You could also make other attachments, such as a blade for the end.
Step 6: You're Done!
The last picture is what i did to a pen with this, I made a sort of gradient for you to compare the before and after of sanding off the lettering.