I find it still really hard to make male friends as a male. I've even gotten numbers from other guys who I've met at a bar and had a blast with all night, but it's still just a little bit weird to call the guy afterwards. In order to make male friends, I think it takes a shared interest in something and repetition. Maybe through a meetup or a weekly rec-league dodgeball game or something that you wouldn't hate dragging yourself to.
Making that first step _is_ tough though. Good thing is that it's usually the toughest.