Chastity is one of those things that seems simple. Just lock up a cock in a chastity device and your done, right? Wrong. I had about a one week lock up in a CB6000 years ago and it was quite a disaster. It was painful and not all that secure (it's easy to pull your cock out).
If I ever experimented again, it would be with a steel cage. And, or course, there is no true anti-pullout protection except with a penis piercing or a full belt.