Strad-style graduating tool; marking

We know from marks on his instruments and shop notes that Stradivari used a graduation punch like this one to measure how thick/thin to graduate his plates. At least, so we're told in this maestronet thread, with directions to make a punch like this.

http://www.maestronet.com/forum/index.php?/topic/329084-video-on-strad-graduation-punch/page-2

https://www.youtube.com/watch?v=LLNAsAr59ws

I thought that looked feasible. Low-tech solutions can work really well.

Shop-made tools are supposed to be a show of workmanship. But they can also be makeshift. I have three tiny children who make it exhausting to get to Home Depot so I seized the day (rather, the naptime) and just used scrap plywood and a bolt I found in the garage. For the hinge I used the wooden handle tip of one of my kid's paint-brushes. Everything is put together with white wood glue.

To sharpen the bolt, I used a poor-man's-lathe. I tightened the chuck of the drill around the bolt head and C- clamped the drill to the bench. I pressed a file against the revolving bolt and hey presto, a sharpened bolt. Before you protest that a sharpened bolt is just a screw, remember that the close spacing of the threads is a plus here for minute adjustments. Some bolts have the screws calibrated for mm -- a quarter turn equals a mm or something like that -- to such a precise degree that astronomers use them in telescopes.

My screw didn't seem to have that, but it still worked. It worked quite well indeed. I used my Harbor Freight calipers to set the clearance between the leather pad (not pictured) and the tip of the screw, poked all the spots of the plates that were supposed to be that thickness, and then tightened it to the next smaller thickness and so on. It took about five to ten minutes to mark the plates.