An option I'm considering... extruded aluminum 80/20 framework. I've used this a lot in the past for industrial projects, work stations, equipment mounting stands, ect.. I found a link today for a model railroad benchwork supplier that is using 80/20 for his modular benchwork product line. Being aluminum, 80/20 is lightweight. Being a profiled extrusion, it has a lot of rigidity. The slots in the 80/20 allows for t-nuts and bolts for the connection hardware... which provides a lot of flexibility. All you need is a cut-off or chop saw to cut the stock lengths into whatever length you need. The 80/20 product line is very deep, with just about every bracket, cap, leveling foot, brace you could want or need.
http://www.engineeredlayoutsystems.com/ shows what I am referring to.
