JKS, I have 2 turtle traps, and they've worked very well for me. I only set them out when turtles become a problem during feeder throws, and once the numbers go away, I pull them out. A turtle or two at the feeder is ok with me, but 10-20 isn't. I bought mine from Boatcycle, but some folks make their own.
I've never caught a snapper in one.