Here's one easy to build, Easy to take in and out of the boat. Works great..
Smith
I built mine out of a piece of flat metal 3" wide X 1/8" thick Made mine long enough where it was at the right distance from my seat. Cut a half hole. Then welded a pipe nipple on the end of that. And then drilled a hole in the side of that Weld a Nut over the hole. That way you can screw a bolt in to tighten it again the padestal riser. Then after rounding all the edges on the flat iron. I welded a 2" piece of pipe on the front of that. Then drilled a hole and welded a nut again the same as the back. Then a piece of pipe that fits inside the 2" piece. ( Also i had the black pipe in 2" So that is why I went with that 1 1/2 would work just as good.) That or 2" Sq Tubing then 1 1/2" inside that . This way you can adjust it for the height if needed.
Then your bar across the top for the rod holders. 5/8" Cold Roll Steel works perfect for the The HI-Tec rod holders.
Also glue Carpet to the bottom of this helps keep it in place. That or Rubber.
Pete