I had tried a few plugs for the typical 5 mm holes in cabinets, but wasn't really happy with any of them. Either the holes weren't covered big enough or they weren't rounded on the outside contour, which doesn't really make it aesthetically pleasing.

So I designed a simple 5 mm plug with an outer diameter of 15 mm and a height of 1.5 mm. The outer contour is rounded and due to the 100% filling you don't see any shadows from light falling on the lid, as I had with other stoppers. 

The tip is rounded at the front, which makes assembly a little easier.