for whatever reasons, my local grocer has oogly bits of meats available on mondays, and that often includes neck bones, oxtail, marrow bones and "soup bones". it's cafo meat, but i use it anyway for broth. if you have a local butcher, the real-deal kind, they should be able to sell or give you bones. they go for short money too. i've gotten shank, "foot" and tendon at a southeast-asian grocer.
same deal as making chicken broth. i use carrots, onions, garlic, bay leaf and thyme. ginger if i have it. peppercorns. cover the bones with water, bring to a boil, then simmer for 24-36 hours. the bones should be soft when it's done.
strain out all the solids, reduce and portion to store and freeze. i do about 15 pounds of bones at a time.
As I ate the oysters with their strong taste of the sea and their faint metallic taste that the cold white wine washed away, leaving only the sea taste and the succulent texture, and as I drank their cold liquid from each shell and washed it down with the crisp taste of the wine, I lost the empty feeling and began to be happy and to make plans.
– Ernest Hemingway