I talked to John Watson at the Citrus Center, and he said that they have found 4x4x14 tree pots from Stuewe & Sons work the best for them. I bought a case of pots ($0.41 each) online, and started building my table as soon as they arrived. I am glad I waited until the pots arrived before I bought a sheet of remesh. I don't know where they get the mesh they use in Weslaco, but the remesh at my local Home Depot had 6x6 holes, and was just too big. I couldn't find any other metal fencing that fit the pots well, so I just picked up some wire.
Once the kids went down for their naps I got to work. The dimensions are roughly two feet deep, three feet tall, and five feet wide. Instead of using metal fencing to hold the pots up, I just used wire. I drove nails every five inches along the top rails, and wrapped the wire around them to form a grid. This actually worked out very nicely, and was cheaper than buying a sheet of metal fencing that might not have fit well anyway. The finished table holds 56 tree pots. I had planned to get all of my rootstock seedlings transplanted, but I was out of town most of the weekend, and just didn't have time. I'll just have to find time to get it done sometime this week. John Watson says that by using a good potting soil, deep tree pots, and Osmocote, the Citrus Center is able to grow both sour orange and trifoliate rootstocks to grafting size in one year. I hope I'm able to do it too, and that I'll have 50 rootstocks to graft and share next winter. I'm planning on building a second one for grafted trees that will go in the greenhouse when it's finished.