To test that everything works before I commit to wood. I printed up a test jig. It needed a little refinement to open up the bores (3d printing is not perfect for dimensions, esp of circles). But then. I could test fit everything.
And it works.
It works better than I ever dreamed it would. The bar in the image slides easily, but with just a quarter turn of the bolt. It locks on place. A quarter turn is all it takes. From free moving to locked. Now I need to buy the wood.