When I lived in Washington my local commercial plywood supplier carried MDO/signboard with the plain brown phenolic faces. It's great for jigs, fixtures and utility construction if weight isn't an issue. Now that I've relocated to northern Utah, about 75 miles of Salt Lake, no one knows what I'm talking about. All the local wholesale building suppliers have is form board (for building concrete forms), which is similar but not quite the same stuff, plus it's got lots of printing on the faces. Any ideas on where to look?