The post is a 4x4 pressure treated lumber fencing post. This comes in 6’ pieces, which is the perfect length for this project. The top of the post is a scrap of 2x6 pressure treated lumber. Some stores sell this in small 4’ pieces if you don’t have a scrap. Cut the 2x6 to a square.
Attach the top square to the top of the post using wood glue and 2.5” outdoor wood screws through the top of the square and into the post. Make sure to line up the top square on the center of the post.
Next, add your finial. This is an outdoor fencing finial. There are several different styles to choose from. Drill a small pilot hole in the center of the top of the square and attach the finial by turning it into place with the attached screw. I also like to add wood glue in between the two pieces.