Kevin Whitlow had a great suggestion on cutting Kevlar; go to the store and buy several pairs of really cheap scissors. They will not last very long, but a couple pairs might get you through a set of tanks.

I just did a set of tanks using 3.3 oz Kevlar. I used 3 layers, which was just barely enough, 4 or 5 layers would have been better (but I ran out of fabric).