I think (as a few others have said) education with the tapers in the packet or on the wrapper would be good. When I was at school stretching was what the lads did because they couldn't get facial piercings or tattoos, I know some people who have stretched bigger as they got older and I know some people who have taken them out and they've pretty much gone back to normal. I didn't stretch until last year so I was 24. It really hurt, which I now know is a big no no - but what can I say? I thought I did it right at the time so it's not just 16 year olds who are dumb lol! As for age restrictions well I think like all body mods they're a journey and an experience so let them have their fun. I remember at school guys used to pass their tapers on when they'd finished *shudders* and use random stuff like corks from the science lab to stretch up. They all said it hurt and the faster you stretched the cooler you were - I'm not saying it's responsible by any means but I have to say no one had particularly horrible results.