Used my 8gal brew kettle and emptied all the bones and carcs from the freezers into it (after roasting of course). Included 5 turkey feet. Kettle was full to the top by the time the bones were appropriately submerged. Simmered for about 18-19 hours then added quartered onions, and coarse chopped carrots and celery. Plus some herbs. Simmered for another 1-2 hours, the strained and now it's reducing. Should get at least 2.5 gallons, maybe more depending on how much I reduce it.