An article by Joe Brann in the Layout Design SIG's Journal #43 describes a method of making strong lightweight benchwork from thin lauan plywood braced like a Warren truss bridge. This is a wonderful idea. I bought a 4'x8' sheet ($10) and cut it lengthwise into 2" strips, then made a small section of benchwork to test the ease of construction and the resulting strength.
It's great! This test section is only 14"x8" (¾ square foot), but it is very rigid and weighs less than half a pound. The long unbraced side flexes a little, and this would be a concern on full-size sections, but additional bracing would reduce flexure significantly. I used hot-melt glue for this test section, and it works well.
I'm very encouraged by this test, and plan to make all my benchwork like this. I can build "curved" benchwork by gluing short segments of the strips to follow track curves, with a radial brace at every joint, such as this test section.
Truss benchwork is amazingly lightweight and strong. This entire section weighs only 1¾ pounds, yet can be held aloft by a single truss chord on one end, as seen here.
Truss benchwork is very economical. One $10 sheet of plywood yields enough 2" strips to make eight curved sections of this size, or six straight sections 8' long by 14" deep. So a 32-square-foot sheet makes 56 square feet of truss benchwork (more or less, depending on the shape and number of trusses).