Imagine you had a metal tube, with an oval cross-section...
approx. 1" x 1/2". Then say you wanted to pierce a pattern in
one side of this tube. A conventional jeweler's saw is not the
If you've got big bucks (ha ha) you could get yourself a laser &
burn the openings. One of my metal suppliers has a flatbed laser
that can handle 5' X 10' X 0.5" steel or 0.25" aluminum.
Seriously, how about etching the openings. This would require
coating even the inside with resist though.