There are wire strippers like this: <attachment 1>
They can do multiple wires, but may not be wide enough for your needs.
For ribbon cable, I just use a spring clip and hot air gun <attachment 2>. I believe there are commercial units available but don't have a link handy. If I were only doing a few (as is my case), I use the spring clip. Insert the wire, heat with hot air until it is hot enough, then pull. Hot enough is based on vision, timing, a little practice, and smell if PVC.