I want to bring new life in this discussion, 19 years ago when this topic started the topic about devices to prevent masturbation was fairly new, but nowadays there is a lot of development in this area.
I am from a small JW community in Frysland, Holland. A couple of years ago the elders got a lot of complains from parent about the masturbation habits of their children, mainly the boys. Because if the body is your temple, why soil it with this behavior, it's disgusting. The answer was found in devices to prevent masturbation. At the age of 12 the boys in my community got either a cage device, and if that does not work for some reason, they got a Carrara belt. At least 99% is wearing a belt, the rest a cage. The device stays on till our marriage. In the mean time, our parents unlock and supervise the regular cleaning of the private parts.
This has worked out so well, the parent are happy, the boys do not get distracted and on dates with girls no one has to worry that anything happens, that finally I'm ready to share this with the rest. I hope other communities will follow with this custom.