Belts. GT2 belts with spring-loaded idlers for tensioning. Lead screws are overkill for foam — they're slow, expensive, and have backlash issues that belts don't.
The one place lead screws win is rigidity under heavy lateral load, which a hot-wire cutter doesn't have. Belts make the machine faster (300+ mm/s rapids) and cheaper.
The one place lead screws win is rigidity under heavy lateral load, which a hot-wire cutter doesn't have. Belts make the machine faster (300+ mm/s rapids) and cheaper.