Parametric Jig for Music Staff

Tweaked CodeCreations' tool (see source) as the original one didn't work out great for me. I needed the clamps to be longer so that the pens wouldn't flip and fall off all the time, and I needed some kind of bar at the top end to make all the pens touch the board, otherwise they'd always get misaligned.

While I was at it, I though I might as well fix the vertical alignment of the clamps in relation to the frames and add hooks to hang the whole thing on top of the board if you're using a board