Completed Light Assembly

Everything bolted up - there are LEDs inside each of these tubes although you see the left one is the only one with a wire at this point.

The wider hole on the right isn't an accident - the middle two tubes have a single wire entering/leaving the bottom of each (they have a wire between them at the other side - out of shot), whereas the end two need room for two wires in and out the same hole.

See Rob's Homemade LEDs for more about this.