I use the power supply out of an old computer. Each of the connectors for hard drives and such put out about 12 volts. Now the fun part, I plug the power supply into a box with a plug and a dimmer switch. Turn on power supply, turn down dimmer switch until the wire you are using cuts the foam nicely and presto, your cutting foam. Not many $$$ invested in this at all. Crude but ...... it works.
Marty