Grant, for the inlay on this I used the Whiteside Solid Brass Router Inlay Set . It is a really nice set, goes for about $40 at Woodcraft. It is pretty simple to use, but you can't really do anything too intricate.
This is a gorgeous stool. This ordinarily would be a rather simple mundane project but you have certainly raised the bar on this one. This is not a simple stool. The through tenons and maple wedges add nice details to the project. And the inlay is just outstanding.