I used a 3/4 X 3/4 inch aluminum angle and cut it to length allowing about 3/4 inch overlap (flange) at the top and bottom. At this flange I overdrilled to allow a 1/4"bolt to tap into the mast. Some like to tap this hole so you do not lose the bolt when removing it.
next grind off or saw off most of the angle that goes into the mast. you should leave it just thick enough to match the mast extrusion. This is why I like this method more than a flat plate because when the slugs go up and down they will catch on a uneven groove.
happy sailing
clint
