I've been thinking of putting together a magnetic building system before I continue with any of my airplane builds.
I picked up a 3' x 8' piece of 26 gauge galvanized steel at a local HVAC dealer this afternoon for about $15. The dealer is part of a chain, so folks can find them many places. (R.E. Michel Company).
I also ordered 500 cabinet magnet latches, part MAG-123, from All Electronics for a total of $174 with shipping. I'm going to cut my own jigs based on the one on Airfield Models site here. Details on making the fixtures can be found in the graphic in the zip file here. I figure 500 magnets will let me make about 100 fixtures. That should be plenty for anything I'm building in the near future.
I'm planning to build a torsion box as described by the Wood Whisperer podcast number 18 (Wood Whisperer #18), although I am going to do some of the changes identified here: Len's Torsion Box. Instead of making the hardboard removable like the Wood Whisperer does, I'm going to replace the hard board with the galvanized steel, but will use contact cement to put it in place permanently. My overall size when I'm done will have a 3' x 6' metal surface to build upon.