sheet metal intake...

Don't try using a plaama cutter on thick 3/8" metal. I did this for a set of flanges a few years ago just to try it. It worked, going slow and angling the cut, but it surface hardened the metal. Finishing the flanges reguired hard core die grinder work and it wore out my carbide, and it took about three times longer to finish them.
Next time, I'll buy a set that is machined or cut on water jet.