shells from 2 dozen steamed blue crabs*
3 carrots, cut up
2 onions, quartered
1 ear of corn, quartered
1 bunch celery
1 head garlic
1/4 cup black peppercorns
Place the crab shells and the vegetables in a large (8-10 quart) stock pot. Add water until the pot is nearly filled.
After about 4 hours (longer if you used more water and a bigger pot), and the liquid has reduced, strain into a large bowl. If you want it super clear strain through a paper towel or cheese cloth lined colander. Cool immediately by placing the bowl in an ice filled sink. Refrigerate overnight, then skim off any scum that rose to the surface. Package in air tight containers and refrigerate it up to 12 days, freezer bags to freeze up to one year or pressure can.
*I picked/ate the crabs one day and then refrigerated the shells overnight in gallon bags. I also threw in any legs/claws that did not get eaten. They, of course, were pretty well coated in Old Bay.