Concerned about the use of petroleum-based plastics? Now you can get a computer made of recycled cardboard instead. Houston-based Montoroso began selling several Recompute models last April, ranging from a $200 do-it-yourself kit to a $1,000 deluxe version with software installed. The computers are sold through the company website and on Amazon.com. Not everyone thinks it’s cool — the blog CrunchGear worries it’ll burst into flames — but look for Recompute to catch on with ecoconscious geeks.