All of them will leak, but if you don't want flimsy paper, glue it to something like a piece of cardboard, cardstock or another piece of paper when it's dry. It will have to dry fully before you handle it.
I doubt these exact methods would work, due to the amount of plastic in the composite. However, heat would be your best bet. Try wrapping black trash bags around the...
You can use rags instead. However, paper towels are not going to leave fibers behind that could later block your gun when it is in use, causing you to strip...