Inlay the back stripeI glue the back together, thickness it, and measure the physical properties just like I do for the soundboard. Then I inlay the back stripe. The stripe is decorative, but functionalit strengthens the back joint like the gross-grain graft on the inside. I often use solid wood with a line or two of purfling, but I have some marquetry strips that I like too.
This fixture has two movable fences whose edges are perfectly aligned with the router bit. I clamp the back in place and line up the inlay on the center joint. Then I slide the fences until they just touch the inlay. Once I remove the inlay, I run the router along the left and right fences. The result is a perfectly sized groove.