Lacking a quick and easy way to clamp a workpiece to the top of my workbench, I devised the clamp you see above. Its low profile makes it easy to sand or plane the workpiece.
The base is made with two dowel pins that slip into a pair of holes in the benchtop. The holes are opposite a bench dog (photo above). A hole is drilled through the edge of the base and a threaded insert installed. The clamp is loosely fastened to the long bolt with lock nuts and washers. It should rotate freely on the bolt.
I keep a ratchet spanner handy for adjusting the clamp, as you see above. It’s a simple solution that’s quick to set up and use yet stores easily under my bench.