The glow ring as parkers or DRLs as seen on BMWs headlights. Use a pice of clear acrylic rod, bend with heat and then knick the outer edge to refract light. Fit a small LED on one end to parkers line and fit in the headlight unit. You will need to bake the unit in the oven to soften the glue in order to take the headlight apart to get at the internals.