Preheat the oven to 450ºF.
Using paper towels, pat the turkey parts dry, then arrange them in a single layer in a large, flameproof roasting pan. Roast the bones for 30 minutes, then using tongs, flip them over and continue roasting until evenly browned all over, 30–40 minutes more.
Carefully transfer the roasted bones to a large pot. Place the roasting pan over your largest burner (or you can use two burners if that’s a better fit). Turn the heat under the roasting pan to high, then add 2 cups of water. Bring to a boil, scraping the bottom with a wooden spoon to dissolve any cooked-on drippings, and then pour the deglazing liquid into the pot of bones. Add more fresh water to the pot just to cover the bones. (Depending on the shape and size of your pot and turkey parts, you'll need around 7–8 cups of water.) Set over medium heat, bring the liquid just barely to a boil, then immediately turn the heat down to maintain a very gentle simmer. Skim and discard any foam or scum that rises to the surface, then add the carrot, celery, and onion. Continue cooking, uncovered and at a gentle simmer, until the stock has a sweet, rich turkey flavor, 2½ –3 hours.
Turn off the heat, let the stock cool slightly without disrupting it for 5 minutes, then, using a pair of tongs, carefully remove and discard the bones and vegetables. Set a fine mesh strainer over a large container or second pot and strain the stock. (For extra clear stock, you may choose to strain the stock a second time through a cheesecloth-lined strainer. Do not mash the vegetables in an attempt to extract additional liquid—this will cloud the stock and give it a murky flavor.) Set the stock aside, uncovered, until it cools to room temperature, then cover and refrigerate for up to 4 days or divide into airtight containers and freeze for up to 6 weeks.