Thanks Wayne, I'll have a think about which material to make them from. I'll be careful with the port dimensions as it seems crucial to the build. What frequency does that tune them to or is it room dependent?
It looks like it'll all come out of one 8'x 4' and one 4'x 4' sheet of whichever material I choose to use. Can I make braces from MDF or does the hardwood 1" x 2" stock work a lot better?