Duct tape...the friend to that creative part inside all of us.
PVC pipe coupler - check
+
Paint stirrer stick - check
+
Duct tape - check
+
Degree from top engineering shcool
=
One custom made couple holder for a $$$ Lambo. Love it.
So, did you take the koozy to Lowes and test fit the different couplers, or did you use a NASA calibrated caliper and then head to the store for the exact fit? How geeked out did you get.