You can do the same with a cheap Harbor Freight single-speed tool. They sell the speed control also.
You can't use the speed control with a Dremel that already has one built in. I found an old one at a flea market last year, for only a few bucks.
The speed control can also be used with a soldering iron based "hot knife" also, to dial down the heat. It'll work the same way with the soldering iron too.
--Mark