How to make a 2 track commutator. Use an Elektrikit original as a template. Cut some PC board to the rectangular shape  (37mm x 60mm). Take a 5 hole strip and use it as a template to drill the centre hole and the 2 tab holes. Bolt the rectangular PC board to the original commutator and file it to shape. I used the bench grinder to get it close, then a small flat file to finish it. Next, bolt the home made commutator to a 3" pulley and mount the pulley on any old motor. I used a 6 speed Power Drive Unit at 12:1. While it's spinning, push the corner of a screwdriver into the position where you want the tracks separated. It will scratch a gap in the copper plate. Thanks Paul Dale for this brilliant idea! Now use a small file to make a gap to separate one tab from the outer track. Drill 1mm holes in the inside track and the tab and run a link wire between them. This last step isn't absolutely necessary but it makes connections easy with one tab for the inner track and the other tab for the outer track.