There’s an attachment that you can buy at Walmart. You put it onto the top of the spray can and you use it just like a suction feed spray gun. For me it helped me with consistency of application. That and my finger didn’t get tired so quickly.
I painted my whole Datsun with a set of spray cans. Primer –> Base –> Clear
The attachment made it extremely easy for me. It came out pretty streakless. My friend also put a spoiler on the bed cover of his S10. The spoiler was from a Dark Blue Supra and he wanted it black. I sprayed two spray cans with the attachment and it turned out pretty good.