Hi Dead Sled...

In the picture of the okra...the rafts are 2 1/2 pound foam, 2 inches thick ( they might be 1 1/2 thick) They are floating on the water.

To make the holes...I put the bottom of the pot on the raft...then drew a circle around the pot. I used a jig saw, with a scroll blade. The pots fit snug into the holes.
Once the plants start getting big, we support the weight by strings hanging down from the lattice.

For those that like to 're-purpose' items....the lattice is actually sides from baby cribs, that didn't meet the new safety standards. We got them for free.