VHT wrinkle paint
I heat the metal part in the oven to about 170 degrees lowest setting.
Then paint with wrinkle.
Then put back in oven at 170 for 1/2 hour or so. More durable if you bake it. And the wrinkle will be VERY consistent.
I can file my fingernails against my baked wrinkle parts.
Not wrinkle, but you get the idea... I try to bake all my painted stuff.