Rubber O-Ring Cord Stock
O-Ring cord stock to make your own O-rings and gaskets Make your own Buna-N O-rings with O-ring Cord and O-ring Glue. How To Make an O-ring: To calculate the correct length of cord required, (( OD + ID ) / 2 ) x Pi = Length. This will then give the correct length of cord required. Using the splicing aid and a very sharp knife. make a cut in the material at a right angle.