Great pic post Hairy. What do ya recon Uncle Henry is gonna store in his rabbet box? Bunnies, or?? JK, I get the difference rabbit rabbet.
I bought a Chiwanese spline jig based off that WP one. Really hard to assemble, but it does a great job, and the metal ones will outlast about 30 of the Ho Made wooden ones. They seem to widen out at all of the important places, and splines end up getting weird.