Concrete Lumber is a line of posts, beams, joists, and decking made from a patented lightweight concrete reinforced with pre-stressed wire. It’s half the weight of standard concrete by volume and, besides being impervious to rot, will actually flex like wood without cracking. Cut it using a masonry blade on a circular saw and fasten it with screws or bolts. If you want a finish, the company suggests a standard masonry paint but also has some proprietary coatings under development. Cost varies by member, but a 2x6 should cost about $2.50 per linear foot. Concrete Lumber Co., 215.369.1520, concretelumber.com