I'd be more inclined to mark the spot by tightening them a little and taking them off than by beating on them with a hammer. I don't have a jig, but I do have drawing tools like graphing rulers:
http://www.office1000.com/discount/rulers-graph.html
You can get very similar items in the sewing department at WalMart, the big 4" X 24" ones are great for laying out control holes, drawing pegheads etc. If you can mark one hole correctly and you have a ruler and a right-angle or small drawing T, you can mark them all.
http://www.office1000.com/data/c-thrurulerco/JR12CTR.html
Check with a little kid's drawing set - Aaak, do little kids even draw anymore, or do they just watch people draw on TV?
http://www.office1000.com/discount/rulers-graph.html
You can get very similar items in the sewing department at WalMart, the big 4" X 24" ones are great for laying out control holes, drawing pegheads etc. If you can mark one hole correctly and you have a ruler and a right-angle or small drawing T, you can mark them all.
http://www.office1000.com/data/c-thrurulerco/JR12CTR.html
Check with a little kid's drawing set - Aaak, do little kids even draw anymore, or do they just watch people draw on TV?
