Actually there is a 3/32, 1/8, 1/4? set of collets available from
Princess Auto that seem to work fine with #30 and #40 bits in their
cheap 90 degree die grinder. It gets into tighter places that way than
it could with a chuck. I find that it turns too fast though and needs a
steady hand or it will cut sideways like a router ;( It will make a
hole real quick though if you don't have anything else that can get
access to where you are working
Ken

I have an ancient direct-drive air drill I found at a Princess
Auto here in Canada. No gears in it, and it turns at some insane speed
like an air die-grinder, maybe 15 or 20,000 RPM. It sure does a nice
job on small holes in aluminum, very little tendency to skid.
I wonder if it might be worthwhile to make a threaded adapter for a
1/4" chuck and clamp it into the collet of a 90-degree die grinder? Or
are there any pistol-grip die grinders?

Dan