Montana and Kansas have tried this, and it hasn't worked out so hot. Assorted shooting organizations in Montana lost a bunch of (well, all) cases about this. A couple of guys in Kansas just got convicted of making suppressors, depending on the Kansas law to protect them. They haven't been sentenced yet.guns that are made in Texas and stay in Texas are "not subject to federal law or federal regulation."
A law like this does have some value as a symbolic statement to the Federales, but wouldn't be of much value to people wanting to make weapons and accessories that are covered by federal law.