Before he was using a towel wrapped in electrical tape.
Though I hear electrical tape could discolor your frame a little.
Right from Seedbus1 to you:
"put a strip of microfiber cloth around the tube, wrapped it in electrical tape so water wouldn't get to the cloth and mold.
Then cut a piece of 18G aluminum sheet metal to fit around it.
Sanded the sheet metal on the side that is inside. I also sanded the electrical tape a bit just to give the glue something to grip. Also sanded the edges of the aluminum to get it nice and smooth.
Went to the hardware store and got some weatherproof 2 part epoxy that works with soft rubber and metal and glued it on."
And it's just glued to the tape, so if I ever want to take it off, it shouldn't be a problem.