This article looks at IP in low cost 3D printing from the UK perspective. The upshot is, as long as you are not aiming to sell 3D printers and you aren’t trying to sell copyright or trademark-protected objects without permission, there’s a lot of room to work without interference from IP claims.
The Open 3D Printing project has been at the forefront in exploring the low cost materials that make 3D printing–or local additive manufacturing–a reality.
The analysis for US IP is similar. I’ll try to get to that.