For my Bull Run game, I made some print and play ACW buildings I thought I would share. You can get them as a PDF file here. EDIT: Seems like google docs' built in viewer thing messes up the file somehow, be sure to download the original PDF, then it'll show up ok!
Print them out (remember to turn off page scaling) on a colour printer, cut out and glue together. You might want to use cardboard or something to make them more sturdy, I used a frame of matches I built inside the paper structure. You can see the buildings I made in some of the pictures in the earlier Bull Run report.
These paper buildings will do nicely if you need a lot of buildings or have little money, but I have already invested in some resin buildings, as they look so much better and cost about 3-5 british pounds apiece. You will see them in action once I get my port republic table ready. Let me know what you think of the buildings if you try them out!