Get an impulse sealer. Do you have a Harbor Freight near you? They used to be cheap, like $10 - $15 cheap. I use the rolls of shrink tubing. I cut the length of tubing I need, put the soap in and seal both ends. Then hit it fast with the heat gun. Just point it at the soap then away, turn the soap, point for 1/2 second then point it away again. Once the shrink wrap is fairly tight, do it again and get the last of the wrinkles out. If you heat too long, you'll get holes. The whole thing just takes second but it's definately easiest with an impulse sealer.