I've accumulated a pile of misc junk with making a belt grinder in mind. I already have a little 1x30 and its been quite useful. I use it more than my bench grinder anymore. I want something with a little more umph and speed control for different applications. Of course I could buy something, but what's the fun in that.
Is there some inherent benefit or best compromise for the 2x72? It seems to be the fad among the "must have" crowd, but I could just as easily build a belt grinder for any available size belt. I'm not building it with a single purpose in mind. More of a general purpose tool. I've been debating a disc sander on it, but I rarely use the disc sanders I have on my small belt grinders.
As an side, I've also started planning a simple one day build (I hope) of a 1x30 pipe grinder attachment for an angle grinder. There have been times I wanted a better finish, but didn't have enough material left to take that heavy cut it required to get it.