YouTube DIYer Matthias Wandel first built an air-powered wood engine back in 1985. After his followers requested the designs (which, according to Wandel, weren't really fit for public consumption) he designed a whole new wood engine in 2009. Finally, he has recreated that engine and made a video of its build.
This super-cool project is detailed on Wandel's , where he explains the process step by step in case you can't follow along in video form. You're well on your way to having an air-powered wood engine, perfect for... well, we're not sure, but it definitely looks cool.