As far as I recall you have to be over 18 to by any airsoft RIFs.
You need to be a member of a club to be able to purchase, how shall we put this, colour accurate, RIFs.
If you are not a member of a club but over 18 you may buy a two tone.
Plus a word of warning, painting over the two tone will be breaking the law you have to leave it all bright and cheerful.
Follow all the rules so that those that enjoy playing airsoft can continue to do so, fail to adhere and the long hand of the law could ban the sport outright !
Ed