This page offers free downloadable designs for building your own light bridge that is placed over your track's finish line. This design uses infrared (IR) LEDs that illuminate the finish line sensors embedded in the track. Designs are available for 2, 3, 4 or 6 lane tracks. Each design package includes a schematic (electrical) diagram with parts list and a structure drawing with material list. You determine the dimensions based on your track width and other features.