There is NOT enough room inside the MicroRock to access the air supply that way and it is extremely hard to get a good enough weld to be air tight on a thin walled anodized aluminum part like the body of a MicroRock. Anodizing really screws with the integrity of the weld.
Originally posted by just4schaf
Weld/braze a thin NPT nut on there just above or
below the barb hole and drill into the cavity. You
would not have to relocate the barb that way.
It might look a little ghetto though. If you have a
anno job on it, the welding will mess it up.