This project can be used as a basic foam cutter (or a thin plastic bender if you crank up the power). It uses a nichrome wire as a heating element, and a multiturn potentiometer to fine tune the power/temperature. The base is a 50x30 cm flat MDF board, and some rigid steel bar grabs the 0.7mm? nichrome wire.
It uses a microcontroller to generate a PWM signal based on the potentiometer position, and a MOSFET driver and MOSFET to modulate the voltage applied to the wire. The power supply comes from an old computer.
Access plans and download source code from the repository (Licence: MIT)