So I'm getting to the point where I'm almost ready to summon the big eye, but I don't have enough lenses. And I'm going to assume I'll need to try more than once, so I'd like to have a good 30-50 lenses stockpiled. That way I have several chances and can farm him too. What's the best way to acquire the lenses? I have several NPCs in my base, so Demon Eyes never spawn near it, and when I venture out into the wilderness, all I find is zombies. Also, what weapon should I use?