Someone mentioned wood PLA. There was an artist a while back (might have been 5+ years ago) that made bone PLA with bone dust and printed skewed 3D skulls that had bone texture. It was pretty crazy.
Edit: A lot of talk about product design (hey, something I majored in!), way fun to listen to. If anyone wants to learn more about manufacturing, I have a great book called 'Manufacturing Processes for Design Professionals' written by Rob Thompson which describes all the things talked about in this podcast. Well, except 3D printing. Bending, extruding, vacuum, pressure casting etc. would recommend! It also has suggestions on the use for certain techniques, prototyping, small runs and major runs based on tooling costs. Ah, sorry for the wall of text, I love this stuff.