I drilled small hole from inside of saw just above dust partition in line with blade, then made hole 1/2'' to allow saber saw blade to fit. Circle draw with Sharpie inside coupling.
I cut 6'' PVC Coupling in half on my tablesaw (3/8'' deep cut against fence - left 3 small ''bridges'' to keep together and cut by hand); glued each half into 3/4'' Baltic Birch plate with clearance hole using Gorilla Glue.