I threw some scrap together today; aluminum tape, wood, screws, and 20 AWG stainless steel wire. I power it with either a 12 volt battery or a battery charger. It draws about 7 amps at 13 volts, or about 90 watts. I twisted the wire using a drill to make it like a spring. This concentrates the heat in a smaller area and also allows for metal expansion and stops the drooping effect.
Here is a couple of laser cut acrylic stepper motor mounts bent on my hot wire bender.