Here is my version of the old handscrew clamps.
My main constraint was that I couldn't find any left hand threaded rods, so here is how I built with regular right hand threaded rods and simple nuts.
The pivots are made of 25mm diameter pipe sections, which have the good idea to just let a regular 10mm nut enter into them, with no possibility of turning. It makes a low cost solution instead of a solid pivot that would be drilled across and threaded.
There is a pinned nut on the left rod, in order to be able to tighten the grip turning the left handle anticlockwise.
To allow non parallel pieces clamping, the clearance for the threaded rods are oblong.
The main wood is chestnut tree, the handles are from indefinite exotic wood.
Finish is tung oil.
These tools are unbeatable for holding pieces upright on the drill press table or holding little pieces on the bandsaw in order to keep the hands away from the blade.
Here it is.