Our ShopBot table frame is laminated from three layers of 1x12 pine, with a top made from a stressed skin panel. Two layers of 3/4" MDF are laminated to the panel, then a layer of 1/2" ply to cut the vacuum channels into. I really want the top to stay true for accurate parts, especially stepped scarfs! Notice the hole in the center of the top; the shopvac draws through that hole from the bottom.
This is the connection to the shopvac on the bottom of the table. The second hose coming into the t-fitting bleeds air into the system to cool the shopvac. There's a valve on the other end of the bleeder hose; you can see it in the picture at the top of the page. Closing it temporarily gives an extra bit of vacuum for stuborn sheets of ply.
Ball-bearing rollers mounted on the end of the table to make it easier to move plywood sheets.