Thank you for the ideas, I find that to be a very interesting and thought provoking project. When I drill rivets out I use a battery drill with a reverse function, allow a certain number of rings to build up on the bit, then hold them in pliers and reverse the drill to take them off. It's still tedious, though. I tend to use aluminium sheet and one disadvantage for me might be the overhanging bandsaw teeth marring the surface away from the rivet. Perhaps they could be ground down or covered over. In fairness, I rarely get away with an unscathed surface anyway! On a side note, I find that dipping the drill tip in alcohol between cuts stops the aluminium smearing onto it, but if I've used a permanent marker nearby it often gets removed by the excess alcohol coming off the bit...