I have a crappy harbor frieght air tool that takes the 2 1/2 (?) inch thin cut off wheels. it would work better on plastic, it barely makes sparks in metal. I also have a "Blue Point" version of the same thing that is only marginally better. the only time I use it is if I can't get my corded Milwaukee 4" grinder in there where it needs to be. the Blue Point one could just be old and worn out. maybe I'm just dreaming that there is an air powered cut off tool worth a damn... what do you guys use?