I'm replacing cables and wires and have to run them through a few holes in the aluminum of the boat. I would like to protect the wires by putting in some type of rubber grommet or something so they don't rub on the aluminum. The holes are all different sizes from maybe an inch to three inches in diameter. Any ideas how to make your own rubber grommet or something to protect the wires from the edges of those holes? Doesn't have to look pretty. 