Washington's legislation that just passed includes a vague ban on possession of any files/instructions on 3d printing and CNC/milling/basically any manufacturing. As far as I can tell it's potentially illegal to own a book on gun manufacturing processes in the state of Washington now if you're not a federally licensed firearms manufacture.

The law is vague enough that a states attorney trying to make a name for themselves could interpret it that way, yes. However, the law is very likely to be challenged on constitutional grounds. I would not be at all shocked if a proper 1A challenge effectively nullifies it.

Interestingly the ATF themselves have no issue with homemade firearms so long as you register a serial number