Shamus, I wish I could say "yes," but it's built from a SierraWest kit. If you're familiar with SW's kits, however, you know that they're about as close as you can come to scratchbuilding without actually drawing your own plans. Almost everything is board-by-board, board-on-board, and piece by piece.
I do have a scratchbuilt HOn3 tool caboose that I'll post a photo of when I get a chance.