I made mine from two pieces of wood and some wood glue.
- I used 1/4" plywood, starting with a piece about 30" x 8".
- I used the factory-cut plywood edge as the part that rests on the rim.
- I cut an arc out of it that left enough room for 1" clearance from a rear MTB wheel. I figure that will give me room for 165mm tandem axles if I ever build wheels with them.
- To lay out the arc, I just bent a piece of cardboard, held at the ends, such that it went far enough out, and still came back to the edge of the plywood, and traced along the arc.
- The ends of the arc on my dish tool accomodate an MTB rim, but I couldn't do a bmx rim on it (arc is too wide).
- For the back side of the dish tool, you can do whatever you like. I just matched the arc, and left about 3" of space between the two arcs.
This is tough to explain:The pointer on mine is made from a single 3/16" x 1" strip of solid wood cut into three pieces of different lengths. The first piece is a short 1"x1" block, glued near the center of the dish tool, edged up to the inside arc. The second piece is 2.5" long, and is glued to the block such that its length runs along the length of the dish tool. The 3rd piece slides between the 2nd piece and the dish tool, and adjacent to the block. This piece is my pointer. Since all three pieces are the same thickness, friction holds the pointer in place. If friction isn't high enough, a couple wraps of the 2nd piece with some masking tape will fix it up.
Works like a charm.