nickchen, the felt I used is black & matches the pads. The felt is called Prestofelt and is very thin. I purchased it from a Joanne Fabric store.
The 1 1/2 inch ABS pipe was purchased at Lowe's its ID was perfect at 4cm. I used a Tee to make the outer rings. I had access to a radial arm saw. I carefully cut the outer rings first off the Tee, slipping the length of ABS pipe into it for stability and putting a coupling or end cap on the other end to keep the height the same. It took a few cuts and some sanding to get the 1.3cm inner chamber. A small portion of ABS glue spread thin around the inner area of the outer ring holds them in place. I did not use any cleaner/adhesion promoter as it sets the glue to fast. Four 1mm holes are drilled in at the 12, 3, 6, 9 o’clock positions. Staples brand mounting putty (generic Blu-Tack ) hold the Distancers in place on my MS PRO’s. I used a very small amount of putty rolled thin and lightly pressed onto the Distancers outer edge. After the Distancers are firmly pressed onto the wooden MS housings I trimmed the excess putty off the outer edge. I personally don’t see the need for any stronger adhesives.
Thanks for all the great information and the Head-Fi community.