Without an automatic roll paper dispenser, cutting the paper the way carnie describes is the way that every lab tech does it. It is a simple, straight forward method that saves space as the operator is dispensing the paper vertically and then rolling it towards the lip of the box which will serve as an anvil for your cut (use some sort of straight edge, x-acto or olma). You'd have to be a complete beginner or a klutz to crimp the paper using this method.