If you make a lot of soap, I want to help you save time and money. We have all watched plenty of videos in which nice, talkative ladies fiddle with scissors and tape for 15 minutes. This is not one of those videos.
This method is of my own conception. It really isn't for dabblers, but for the committed! It requires a 'jig' that is essentially a block of wood that will fit into your soap mold. Mount this block of wood to a pair of feet and attach the feet to a base, and you'll be the fastest and best soap mold liner in your town!
I also describe my molds in this video. They are also very efficient and easy to use. I have 10 of them and made them all at once, cutting all of the like pieces at the same time so they are identical.