The one Clint made was I believe 2'x2'x6' he built it for one exact spot where the water was just way too fast to set. If I recall right it was made of 2x4 horse panel weight over a hundred pounds. But his first check I think he had a beaver and an otter in it pinned by the water against the down stream side. Pretty much he relied on the speed at which the critters were moving through there to slam them into the trap and it worked very well for him. I'll see if I can find the video quick