I have read a bunch of posts about the best way to power a hot wire cutter or a convenient way to charge flight packs at home. I just started using a computer power supply.
The one I am using was pulled from an old 486 I had laying around. The drives in computers run at 12 volts DC. And the supply is rated at 8 amp. max current. So its just right for powering your flight pack quick charger. You could even power several chargers off of one supply. It's already in a nice box so you don't have to do any circuits work like some of the posts tell you to do to build Radio Shack transformer. All you needs is a wire striper.
For hot wire cutting I use my charger to regulate the current to the cutting wire. So powering my cutter is just like charging flight packs. Any supply from a 486 or pentium computer will work. Don't buy or make a transformer, when you may have one laying around!