John Lucas
>Jorge

You can build your own vacuum chucks using faceplates and various adaptors made of wood, PVC or aluminum. I used 1 1/4" nuts and welded a Washer to the front then mounted wood on that and then mounted PVC pipe to the front. I've also made some out of wood but you have to seal the wood or it leaks air. The pipe or wood is really just a bowl to with a rubber lip that forms the seal. The bigger the bowl the stronger the vacuum hold.
Packard sells gasket material that fits on the rim of the vacuum chuck. I use that but have also used The gasket material that goes between my topper and my truck bed. It isn't very tough and wears out fast but a huge roll is only $6. Since it's not round I connect the joints with silicone rubber. This has worked fine for years but the real gasket material is better.