Here’s one. Sometimes I make this set if I have a cat getting my beaver and occasionally (god forbid) an otter. I can make this set with one of my #4 traps and as long as I keep the trap in the water, it’s a legal set.
Find some shallow water 3 to 6 inches deep. A cat will readily wade in shallow water. Get a log about as big around as your leg. Position the log so that it points toward dry land an the end of the log is 18 to 24 inches offshore. Put some kind of “bait” in the middle of the log. I usually use a chunk of beaver, and wire it in place. Bed your trap in the mud about 6 inches off the end of the log. You can fasten the trap right to the log if you want. (I do this with a snare extension cable.)
Of course, this is all predicated on finding cat sign in the immediate vicinity. This is not a good set to make at random.
-- Hal