I'm also planning on installing ceiling beams in a great room in my house. I worked in a restaurant years ago that had imitation wood beams made of plastic. They looked great. I can't find anything on the internet related to these. I've also been considering using a thin cheap wood to get the size of a beam, then just add a veneer (1/8th in.) to cover it. Good luck. Let me know if you find anything sturdy, light, and esthetic.