I have a range of pneumatic hand held hammers or "zip guns" as they're sometimes called.  I use these tools primarily for incising work on steel and they can do a pretty good job for incised work and for carving as well.  I use them more for heavy incising work than carving though. Well, I've never tried to do any chasing with these tools so I'll give it a whack now and see what happens.  Most of the bits are ground for incising work but I do have one blunt tool that's useful.  I'll have to now make up a couple of new bits for the job at hand. The bit inserted in the tool was just formed for what I need to do right now.  I simply cut off the end of a useless bit that I had then heated the extreme end.  After setting aside the torch I then triggered the tool, driving the heated bit into the steel table plate.  This upset the end to broaden the face of the tool.  Next I ground the tool to give it a slightly rounded face and radiused the rim.  This will be used for flattening and forming areas on the sheet metal.   I then made another bit with a straight across flat face but didn't upset the end so the face is the same size as the shank. This tool will be used for running up against areas to be angled and also for some flattening work as well. A couple of points of interest.  After heating the first bit I find that I don't need to retemper because the steel was hard enough as is, maybe because of the relatively quick air cooling that simply happened.  The second point is that these bits can be purchased very cheaply in sets and even though the end shapes are standard tools, you can cut them off and reshape the rest of the steel.  The steel in the cheap imports that I found is excellent and is a source of inexpensive starter material for further reshaping. By the way, if you're wondering how I cut the unwanted portion of a chisel away, I use an abrasive cutoff wheel on a die grinder.  You can't run these things through your bandsaw and expect to have any sharp teeth left on the blade afterward.