I often draw forms with no model. I am sure this is probably not the recommended way to learn, but it’s what I do. I’ve always been one to draw from my mind rather than from my surroundings. When I was in school my art teacher, Sister Agnes, used to get really irritated with me for not copying from other pictures. She wasn’t a great art teacher, but art class was a great way to get away from the chaos of being a teenager for an hour or so.
Sister Agnes, would not approve of this, but then she doesn’t have to.