I make at least half of my cookie cutters by hand. I use the cardboard/exacto knife method for shapes that I don't think I'll reuse, or if they are really intricate. But I actually prefer to make them out of metal because they are washable and then you can use them forever. To locate the metal, I just looked in the yellow pages and found a sheet metal company. They cut me 50 COPPER stripes for $50. I have found that if you buy a thin enough gauge and work with 1/2" strips - you can shape them a lot easier
However, I bumped into a friend from grade school at my 20th high school reunion last weekend. He happens to own a steel company. Wow, never thought I'd be so happy to have a friend in the steel industry!
He told me that the copper cookie cutters you buy at the store are coated with something which keeps them from rusting, but that the copper I had acquired was NOT, which is why I've noticed rusting on them. Woops! Time to change that in a hurry.
He said what I should use - here's the big tip - is 304 or 316 Stainless Steel. It's readily available from sheet metal companies. Duh,
why didn't I figure that out - all of my stainless steel tables are also made of 304 stainless steel!!
Anyhow, I don't know what the costs are for the steel because naturally I'm going to barter w/cookies!