The large cutouts were cleaned up using a punch nibbler and files. The actual instrument was used to make sure that each hole was "just" large enough. The holes for the 2.25" round instruments (COM and AP) were drilled with a Bi-Metal hole saw. The holes for the vents were drilled with a 2" Bi-Metal hole saw. The remaining small holes were drilled using small drill bits and the larger holes were drilled using a step drill bit. All the cut surfaces were deburred.
