Find the center of your plywood square. Be aware that if you got a scrap piece of plywood it may not be exactly two feet in both directions. Ours was 23 7/8”, so we had to adjust accordingly. Measure out from the center to find the exact square where your 4x4 post is going to sit. The 4x4” post is actually 3 ½.” (I forgot and had to eyeball it within my markings.)
With a bit that’s a little smaller than your screws, drill four holes inside the square. We used some more scrap wood to prop the plywood off the ground.
Place your post upright on the ground and set the plywood on top with the markings on the square matching up with the post. Grab a hammer and a couple of nails and nail the plywood to the post to temporarily secure it. Now it can’t angle itself accidentally as you secure it.
Drill your screws into the holes. We picked long screws because you’ll be drilling with the grain of the post, and it’s harder for the screw to grab onto something. The longer the screw, the more secure it’s going to be. Just make sure that the head of the screw will embed itself into the plywood so that the bottom is flat.
Now it’s time to cut a rug. Literally. Cut your carpet into a 2x2 square. We cut ours a little bigger than the plywood and then cut it down to exact measurements later. Cut out another piece of carpet 24x18”, and one 4x4”.
Measure a square in the center of the carpet just like you did for the plywood. Cut it out with scissors or a sharp knife; cut a little outside the lines that you drew.
Staple the small piece of carpet on to the top of the post, and staple down on all four sides. You may want to staple down the corners too. Wrap the 24x18” piece around the post and tuck it down inside the bottom carpet. Staple the carpet down on all four sides of the post and all along the edge where it overlaps.
Measure the plywood and then using a miter saw cut the opening trim accordingly at a 45° angle to border the bottom of the scratching post. Match up the trim with the edge of the plywood and hammer in the finishing nails every few inches. Add the bumpers to the bottom four corners.
Grab your scissors again and cut the carpet wherever needed to fit inside the trim. Staple down the carpet along the edges, and you’re done! Enjoy!