The little criss-cross anti-racking device in Benchcrafted’s hi-vise kit is such a neat mechanism, I wanted to make one. Mine’s made of three ¹⁄₂" aluminum bars.
The jaws are from the same big slab of mahogany as the electric ukulele.
The screw is a ³⁄₄"-6. I originally had a 4" wheel on the end, but turning it was way too slow. So I drilled a bar through the screw and made a little cap from a spacer.