I want a vacuum table!

[Jonathan]

It's rubber to get a high coefficient of friction, so for a given vacuum pressure (i.e. close to atmospheric pressure) you get a higher holding force than a more 'slippery' material.
The small hole is there so that when the seal is broken not much air can flow through, which reduces the power required from the pump to maintain the vacuum.

If the system is sealed then (ideally) zero power is required to maintain the pressure difference and clearly the power required goes up with the size of the aperture to leak through. If you don't have their mat and cut through, the apeture is large (the size of the cut), so it's difficult to maintain a sufficient pressure to hold the part. If you keep the apeture small by only 'revealing' a tiny hole when cut through, as their mat does, it's then possible to maintain sufficient pressure as the leak is only small. When you first clamp the part, you just need the hole to extract the air in a reasonable time, so a tiny hole is fine as the air volume is small.

You could probably achieve the same thing with an array of O-rings positioned in an array of cutouts on an aluminium bed, with suitable channels to direct the air underneath and a very small hole in the center of each ring. Some eperimentation with the size/thickness/amount protruding/type of rings would berequired, but once you've done that it's a cheap system to maintain as the O-rings don't cost much to replace. I'll try it when I get my vacuum pumps working.