snrub - Visualize a B trap as half of a cloverleaf trap. Maybe not the right tool for catching catfish. My Grampa Wilkie used a lot of slat traps when he fished commercially on the Missouri River. He built his own, but they were very similar to this one: https://www.netsandmore.com/products/fishing-accessories/slat-traps .
Couple of good videos associated with the traps. Thanks!