Portable Electric Sanding & Sharpening Pen

I was a little skeptical that this would be worth the price. It is!!
There is almost no run-out and very little vibration (your hand causes more movement than the motor).
I have not needed to recharge the battery even after several hours of use. It has plenty of power to cut through plastic, wood, UV cured glue, epoxy, etc... It would probably scribe metal with an appropriate ball mill.