I'm lazy so I just take a Costco chicken, remove the meat, break down the carcass enough to fit well in my pressure cooker, barely cover with quality veggie stock (I did mention that I'm lazy) and cook on high pressure for 1 hour.

When not lazy, I roast chicken feet in an oven with large chunky mirepoix at 425°F/218°C for 45 minutes, moved then around in the pan to avoid burning, then another 45 or until nicely browned. Deglaze the pan, pour all and liquid (water or the box stock) in the cooker as above.

The regular stock is a gelatinous mass in the fridge. Foot stock is akin to vulcanized rubber.