Living in TX, occasional seller at gunshows out-of-state
Of those states only Utah and California require state-specific licenses to sell guns at a gun show. In California, a valid Federal Firearm Dealer License (FFL) and a California Certificate of Eligibility is needed to sell firearms at a gun show. Utah also requires an FFL along with a Utah Transaction Form for Gun Dealers. Both Nevada and Arizona are unregulated in the sense that they only require an FFL to sell firearms. And all four states require a criminal background check through the National Instant Criminal Background Check System (NICS) of the customer before selling a firearm.