How can I make my own perforated edge?
A sewing machine without thread does a great job at making a perforation in most paper. Depending on the settings it can be rather coarse, or quite fine. Much of this will depend on what stitch types your machine is capable of. I would not use your nicest needle however, as it will most likely wear prematurely.

Otherwise, there are purpose built perforators available for ordering online, that work much like a rotary paper cutter, with the obvious difference that they do not completely sever the paper.