I worked out the details for this light. First I used a wooden toy wheel. I think it is a 1/2 inch. The LEDs are 3/16ths diameter so I slightly enlarged the hole for the LED only. I wanted it to protrude just a bit below the wheel. That give the best effect. You want to see some light from the side view. The wheel was rounded on the top edge. The plastic is just a holder. It will be super glued to the LED since the LEd is not sitting in all the way.
In the holiday spirit these are Xmas markdown LEDs.
I originally was sanding the bottom of the wheel to expose the bulb but all you have to do is push it through. It is a tight fit.
After the wires are connected, I will use a gray piece of insulation from a strand of phone wire to cover the green holder.