Well, as we shatter all of the fantasies of no pulling out without piercing at once -stop lying to yourself, you can just pull your dick and masturbate. Although there's an actual way to keep yourselfes locked up permanently and I do think this is the way to make long-term chastity work decently. You just keep your ball-trap on, well, balls. Find narrow enough cage where balls do not slip out between cockring and tube(metal only, since plastic deforms just enough to pull out). As you go pee or to the shower - you pullout without the keys, if erection comes into place - you quickly push the penis back. Same goes for 'nocturnal' erections. You just pull yourself out for sleep, and push back in as soon as you wake up and is calmed down. Report any erections outside nighttime to your domme for punishment and you are good to go.