After reading all the post on TBHs I constructed a version to put the wild bees into. (If you go to bee forum you can read my post on how that went) Basically I built the top bars out of scrap popular and the hive out of scrap rough cut ceder. I made it so that it would fit medium frames in case I need to install a bee package or I can use the perma comb for the honey flow. The side bars are added to maintain bee space on the sides and give a little strength to the comb. I did run a kerf down the center. I also used a router to cut a 1/2 a bee space on each edge to form a full bee space between each top bar. I realize this hive does not keep in the simplicity of a tru TBH but it does not have the complexity of a reagular hive and frames.
http://users3.ev1.net/~beachwalker/image007.jpg
http://users3.ev1.net/~beachwalker/image008.jpg
http://users3.ev1.net/~beachwalker/image009.jpg
http://users3.ev1.net/~beachwalker/image010.jpg

Wish I had gotten the bees into it so I could give you an update on how it works.