Instructables user BobS has put together a guide on how he built his greenhouse on the cheap from recycled materials. His greenhouse measures approximately 17' x 13', with a height of around 8 feet. For two years, BobS collected suitable wood, glass and other materials to construct his greenhouse.Once he had his materials, it took about 2 months full time to construct. Granted that's a lot of man hours, but the only tools he used were hand tools, an electrical hand saw, a planer router and a battery drill. See Instructables for the complete guide.