I have been aware of "Ted's woodworking" with his "16,000 woodworking plans" for some time. From time to time I get emails from people who want to buy an ad on my website to try to sell the plans. If I have the sense that they are new to advertising, I point out that I don't take ads for the "16,000 woodworking plans" scam in my initial response, because that's usually what they are trying to sell.
Begin by cutting off a 10-in. length of the board and setting it aside. Rip the remaining 38-in. board to 6 in. wide and cut five evenly spaced saw kerfs 5/8 in. deep along one face. Crosscut the slotted board into four 9-in. pieces and glue them into a block, being careful not to slop glue into the saw kerfs (you can clean them out with a knife before the glue dries). Saw a 15-degree angle on one end and screw the plywood piece under the angled end of the block.