bending plywood for a diffuser

i want to put a curved plywood diffuser directly behind my window. can anyone tell me how this is done. both how you curve it first and then how you keep it curved

Try here, two thirds of the way down. http://www.johnlsayers.com/phpBB2/viewtopic.php?t=1637&postdays=0&postorder=asc&start=0 Have fun!

There is a such a product called "Bendable Plywood". I've seen it, and asked Home Depot the other day about it, and they can custom order the stuff, but I think it's relatively expensive. I don't know how well this stuff would work though????