The first Vac-Clamp was made for a home built CNC router because vacuum clamping was expensive. It was made from scrap plastic, and a very noisy and inefficient venturi, but it did quite a reasonable job. A cabinetmaker friend noticed the vacuum clamp and borrowed the clamp, and never gave the thing back.
This meant that a second clamp had to be built, but not just for computer controlled routers. It also had to use less air, and be a whole lot less noisy. A cast aluminium base was made, and a more efficient venturi was added. A rubber seal was glued to the top, and VC1 was made. This was very expensive, but worked very well.
VC2 was machined on a CNC machine in engineering grade plastic, and had the venturi built into the body. This bolt down item also allowed configuration of the clamped area which is identical to current day clamps
VC3 was the double sided version of the VC2, and both clamps were hand assembled. There are still many of these in use.
Injection moulded clamp bodies brought the current model VC4 and VC5 to the market. The face plug kits were developed for CNC machines to give better lateral work holding and give a better edge finish
These products are now available worldwide via many resellers