Earlier this year, I read a blog-post that made think -- "That is a marvelous idea. Why have I not thought of this or even heard about it before?"
Here is the link to that blog-post .
Finally with a little time to get something done, I threw one together with scrap I had around the shop. I made the main holding area wider than in the original post, because I want to use it for violin plates.
I don't know that I have the optimal size -- this is literally from scarp around the shop. I had a piece of plywood that size next to the bench. I used a section of old 2x4 for the part that hooks over the bench, and a small piece of pine for the stop at the far end.
Here is the bench hook unhooked. Try it; you'll like it.
On the another front, I have a couple fiddles with their final coat of varnish on. My latest (left) and an earlier one which I have stripped and revarnished. Out catching some morning sun.