I just did a few days of perpetual bone broth.
I do like others have said in the crock pot. Then after the first 18 - 24 hours I scoop out about a quarts and replace with water. I keep doing this until the broth is pale yellow for chicken broth or just paler for beef broth.
I got several quarts and several pints from the last batch.
Oh, we get our beef bones when we get our 1/2 cow. I just tell them I want the soup bones and freeze until I am ready to use them.