Worn out Shop Vac, 2x4's, 9ply plywood and a grid system of holes, surfaced top... And I can cut sheet goods without issue. The picture of my 4th axis captures the vacuum table....
The vacuum table is held steady by cam-clamps. There are (4) 2x4 cross members inside the table. The top is only screwed down and sealed on the seams with silicone. This way, if I need to replace the top before I get my table modified for the Fuji Ring Compressor, I don't have to destroy the vacuum table in the process. I didn't even worry about jointing the edges of the 2x4's, as the silicone and surfacing the table would correct the abnormalities.
I have tried to dislodge the panels and I cannot make them budge. Putting channels into the table for making smaller grids using gasket material, would make it more universal... but for my projects, it was not necessary.
I have a 10HP Fuji Blower (New for $800) and a 10HP VFD (New for $1K) to take the place of the shop vac.
I am making my own table extension for my Techno Isel table, as $3K for a 6" x 50" factory extension kit is waaaaaay over the top....
I cut dozens of panels below, on my $50 vacuum table... and charged $225 for each 4'x8' panel I processed.. pretty good ROI
Dave