It needs to include some way for the snare to tighten and hold the tension. The animal pulling on it cinches it ever tighter. I remember reading that you could use a bent penny with some holes drilled into it to act as the tensioner, but I never really figured out how it works. Snares are not a legal way to hunt here, likely something about them catching too many of the neighbors cats, I would guess.
I suspect that a break-action air rifle and a couple of tins of ammo would also be
enough to rest assured that you could eat all the small critters in your neighborhood if it came to that. You can get a decent one for about 100 bucks, and it is a great way to practice shooting without all the noise (and cheap ammo to
boot!).