I simply download pictures of whatever mobs I want to make and minimize them to an appropriate size and print out a sheet of them. Here's an example of a group of kenkus that I made a while back.
Then I use self-stick furniture pads & a round paper punch to make custom tokens. I've found that with my particular punch it's better to use a thicker paper, like a cardstock or construction paper.
Then for storage I simply put them into a fishing tackle box. I've made several hundred that way.