Hi Mike - It's hard to see in the photos, but the patchbox is simply an iron plate held in place by those two big wire staples at the front and rear, that slides out straight backwards with the wire to guide it, and a little spring catch at the rear just to keep it shut snugly.
I handled this gun at the show - very cool. It has that real severe Soddy architecture with the line of the wrist carrying all the way back through the cheekpiece to the diamond shaped buttplate. Jack builds some really stylized neat stuff.
It was fun to see two nice interpretations of Soddy influence at the show - Ken's and Jack's.
Guy