Tiedown collar for stop motion

This is a little design for a collar to make tying down a puppet's foot easier. I was fed up with fiddling around, so came up with this method:
Use a 50mm M3 bolt (grind the head down a bit) inserted through the top of the puppet's foot and into the pre-drilled hole in the baseboard. (You will need to conceal the bolt head inside the shoe or devise something clever. The boots on my puppets have plenty of space) The puppet's foot needs a 3.5 or 4mm hole through it.
Under the table, grab the end of the bolt, slide the collar onto it and up into position. Tighten the central thumbscrew. Adjust tension with the other 2 thumbscrews.

Required:
3 M3 nuts
3 M3 x 10mm Thumbscrews

I have included 2 files. v3_1 has slightly bigger holes than v3, although it is possible you will need to drill them out with a 3mm drill. Do this before inserting the nuts!