I bought a cheap Chinese version of a Noga clamp, with the clever single-knob which tightens all of the axes in one go.  OK, it isn’t quite as nice as my actual Noga, but it was one eighth of the price.  I needed a base mount to fit it to the T slots in my Bridgeport mill, so I turned up a bit of silver steel, tapped M8 one end and with a single-point turned M12 thread on the other.  Also made a collar from 6082 aluminium to stiffen the assembly, and milled and tapped a T nut from a scrap of EN8.

The finished base in use

close-up showing the tapped spigot and T nut

Fitted into the table slot.  Flats are 20mm A/F.  The silver steel body is inset 4mm into the aluminium  disc so it can rotate as it is tightened