The custom boards the person is on

Custom boards: boards with a name, a public description and (for the person who made each) private instructions for what gets suggested, shared by a link; people who join add their own saves. Each with id, name, made_by_user, who else is on it (with) and join_url, the link to send. Make and change them with POST /api/v1/actions/create_board, add_to_board, take_off_board and the rest.