From what I can see in that pic you have a concave side and a convex side.
Machine the concave side first then flip it over and do the convex side.
Just use a stop strip to locate it when you flip it over.
Other than that, I am not sure what has you stumped?
By the way, that is not a real good design in that picture. The grain is running the wrong way. Grain on clamps like that should run 90 degrees to what is shown. Much less prone to splitting.
"If you see a good fight, get in it." Dr. Vernon Jones