If we're gonna keep posting possible solutions, we might want to be more explicit about what "problem" we're trying to solve here.
If the goal is to prevent people from committing suicide... well, yes, they're going to find a way to do it if they really want to, so we're probably not going to solve that one.
If the goal is to keep people from killing themselves at shooting ranges, the best way to do it probably would be for the range not to rent guns, period; if someone has a gun already, they're probably not going to go to a range just in order to do themselves in there. A close second best would be renting only to people who bring a gun, for the same reason.
This would complicate matters for people who are new to the sport and trying to decide on a first purchase, but there are ways around this; for example, someone who doesn't currently own a gun and wants to try some out could go to the range with a friend who does have one... I doubt that most potential suicides would choose to bring a buddy along. (Especially when there's some likelihood that they could just borrow the gun from the friend to do the deed.)
Another alternative would be to rent only to people who either bring a gun or put up a hefty cash deposit (say, several hundred dollars, in cash, not on a credit card). If they're thinking about a purchase, they presumably have that kind of money; and if they're suicidal, they may well not, given that financial problems are right up there among the reasons for suicide. The main problem with this would be security: carrying that much cash might feel a bit dicey, but then I doubt that people going in and out of shooting ranges get mugged too often.
Or a person could put the deposit on a card and have to wait a couple of days for the charge to clear: as good as cash for the range, no security issue, and easy to issue a refund when they're done renting. It would suck for friendless poor folks who just like to rent a gun once in a while, but no solution is perfect... And this would, in effect, act as a "cooling-off" period for a potential suicide, as well; it would fit right in with Glenn's idea of a waiting period for new customers.
Having a competent range officer on duty is a good idea for so many reasons NOT having to do with suicide prevention that it's almost not worth discussing...
If the goal is to keep people from committing suicide with guns (and thereby contributing to the bad rep of the latter), we're probably not going to fix that one, either, short of passing laws we'd all hate and/or think were unconstitutional.
And for what it's worth, this isn't the best idea:
LoneStarWings said:
If you must do it at least choose a private place so you only inconvenience your family instead of random people in the general public.
It really sucks to find a family member who's just shot himself. Please don't ask me how I know this. Choose a private place, by all means, but fix it so you're found by law enforcement -- it's the polite thing to do.