Want to train your boy to get used to a cock cage and extending the locking time?
First, tell him that you'll keep him locked for just a day. Then extend to two. Tease him with your dick in his mouth and ass. Let him know that in order for you to receive a good fucking he has to oblige to get locked for a week. Promise him that you'll unlock him after the 7th day. But here's the catch, if he gets horny during the 7 days period then keep adding a week of locking.
If he has a strong will and would go a week without sex, slip viagra in his drinks to get him horned up. He'll do anything for some release.
One week turns to two, two weeks turn to three, three weeks turn into a month. Do you think he will last a month of waiting without sex? of course not. As soon as you hit the 2 weeks mark, he is fucked. There is no turning back. He will be caged forever. That's how you should trick your sub into permanent chastity.
A clear cock cage teases him to remind him that he has a dick but can't use it while a black cock cage conceals his dick and making him forget that he has one.
He's now belongs to you. Each time he's naked, gently grab his caged cock, look him in the eyes and say "It's not optional".