3/8" hole punch?

[WeAreAs1 at aol.com]

Hello list,

I'm doing some modifications to my mixing board (Yamaha RM2408) and I need to 
make a lot of 3/8" holes (0.375 inches, or 9.5 mm) into which I will mount a 
bunch of 1/4" jacks.  For a few reasons, I would much rather use a chassis 
punch than drill the holes.  Unfortunately, I haven't yet been able to find a 
source for a 3/8" round chassis punch - the smallest ones I have found are 
1/2".  Has anyone seen chassis punches at the size that I need?  BTW, It 
needs to be the small self-contained type of chassis punch (with the threaded 
inner draw stud, like the Greenlee 730 "Knockout" punches), not the type that 
work in a benchtop metalworking press.  This is because I won't be able to 
remove the sheet metal piece from the mixer chassis - I'll have to work on 
the metal while it's in place, so it won't be possible to place it into a 
press.  The metal is thin steel, less than 1/16" thick, so it will be pretty 
easy to punch.

If anyone knows of a tool supplier or manufacturer that has what I'm looking 
for, or know of some trails to follow, please let me know.

Michael Bacich