I had seen on the internet somewhere a while ago this idea. I had some perspex, cut out a circle, had the edge of the circle trimmed down on the outside so the perspex would sit flat and level with the inspection plate aluminium sheet, drill, countersunk and rivet on the clear viewing panel. The idea is before every flight I can look under the wing to make sure all bolts etc are still where they are supposed to be. Pretty cool I thought.
