The only one I know about is grease pencil. There are yt tutes on drawing models with the pencil. But specially that you are interested in hard surface I would use ref images and just standard box modelling. Less snazzy but more controllable.
Does anyone know any tool that allows me to draw shapes and profiles with Wacom inside Blender? I'm aware of Grease Pencil, but the output is always a sketch-like thing. I'm trying to draw shapes and profiles of hard surfaces, like gun parts, tools, furniture, etc. Is there a tool that "straightens" my sketches? My…