Definitely, and yes, a subforum would be a fine way to do it - just like there is with the Processor's forum under Hardware.
The main reason I suggest this is that a lot of legitimate "Help!" threads get pushed to the bottom of the hardware forum when someone posts a build request / build idea thread. Those threads are the bread & butter of DIY sites like this one, so it might be nice to just have them all in a sub forum so that folks can get attention on just those, and the other threads stay near the top where they deserve to be.