i used a giant beef knuckle and chicken feet. cooked it for three days. foze it in ice cube trays and filled several gallon ziplocks with those. i can add one to a single serving of soup or use a lot as a base for making soup.
it really satisfies, though its not very flavorful. i should have broiled the bones a bit for more flavor. its rich, though. busted the big bones up with a hammer after the first day.