Hello chum,
many on here have done it, I think slats has a link in his sig block as to how he built his, failing that smokerbuilder.com has plenty.
To another question you posed ref brioche buns, I had a burger in "meat and barrel" in Portsmouth that was in a brioche bun you could nip along and ask them, similarly 6oz burgers gets good raps, haven't eaten there myself but the review in the news mentioned the brioche buns........
Personally don't like them myself, if the beef is good,the cheese gooey then I want a minimal bland bun just to keep the sauce off my hands
Good luck Tiny