University of Colorado professor Julee Herdt gave students in her design class an assignment: Build architecturally beautiful pieces of furniture.

The tricky part? Undergraduates in this "Green Tech" course were instructed not to buy any materials for the project -- and, instead, search for scraps, whether in alleyways or salvage yards. If students did need to make purchases, they needed to be minimal -- say, at thrift stores.

The eco-friendly design students came up with varying designs that have been on display at Design Within Reach, a modern furniture store in downtown Boulder.