A few states have the same laws regarding suppressors and machine guns. Especially under the 2nd, 9th, and 10th amendments, it's entirely reasonable. But government enforcers are anything but reasonable.
A 3D-printed AR-type receiver is quite viable, provided there is some reinforcement at the buffer tube region. I'd also suggest a unitized trigger drop-in kit instead of the usual pinned separate components.
RE: More Adventures in 3D Printing!