This law (along with similar ones in Washington & New York) is probably due to lobbying from Everytown, a gun control organization co-founded & mostly funded by billionaire Michael Bloomberg. They've sponsored summits to gather politicians & other influential people to restrict 3d printed firearms.[1]

1. https://everytownsupportfund.org/press/everytown-to-convene-...

Yup.

Everytown and Moms Demand Action which operates under Everytown also provide the white papers, testimony, polling, and public pressure.

These bills across multiplenstates are 100% democratic developed, sponsored, and pushed. In fact the NRA denounces Everytown and it seems unlikely they would be in cahoots behind this push.