A catfish slat trap is an elongated box made out of wood-oak slats. The box is designed with a funnel-shaped tapered inlet on one end. The baited trap is placed in a stream; the catfish can swim in but will not find its way back out.
Cut the oak boards lengthwise with a table saw, making slats about 2 inches wide. Construct a wooden frame with the dimensions approximately 2 x 2 x 5 feet.
Nail the slats to the sides and bottom of the frame lengthwise, leaving a 1 1/2-inch space between the slats for water to enter the trap and small fish to get out. Leave the two ends and top of the trap open.
Construct a door on one end of the box with the same frame-and-slat construction used on the sides. Attach the door to the box with hinges.
Construct a wooden funnel-shaped entrance by making two square wooden frames. The first frame will have the same outside dimensions as the end of the trap. The second frame should be about a quarter the dimensions of the first. Form the two frames into a funnel by nailing slats about 1 1/2 feet in length from the inside of the larger frame to the inside of the smaller frame. Make two funnels in this manner.
Stack the two funnels inside each other and place inside the box, with the narrow end of the funnels facing inward. Fasten one funnel to the open end of the trap. Fasten the second funnel 2 feet from the open end. Finish enclosing the top of the box with wooden slats.
Place rocks in the trap to submerge the trap in the water. Bait the trap with cheese or other bait. Place the trap in a stream with the funnel end facing downstream. The fish will swim upstream, into the funnel, and be unable to find their way out.