@Coelacant1 An aquarium air pump and a 3d printed nozzle is all you need. Nozzle needs to be close to the surface. Hope you get some success with it :)
@Coelacant1 You can either cut with plasma or melt through plastic. Air assist will help make plasma but won't help melting. You know plasma is working because it flashes as it's cutting. cleaner edges too...if you can get it to cooperate
@Coelacant1 neat gadget! try a marker pen on the surface and use an air assist nozzle. the pen ink will absorb the heat while the air will help make plasma to cut then cool the plastic