Someone did a really good job at making Kakariko Village from OoT in Forge. Here is his topic:
http://www.gamefaqs.com/boards/960512-halo-reach/56657286?page=1&tc=Graym8
By the way, when are we going to start doing custom games?
http://www.gamefaqs.com/boards/960512-halo-reach/56657286?page=1&tc=Graym8
By the way, when are we going to start doing custom games?
then I was 
when i remembered that reach only has one style of walls and blocks.
