Made some center caps for my 2118s using some "Renault" caps off ebay and some 60mm x 2mm perspex tube. I measured the gap between the hub lip and the edge of the wheel, which is 9.5mm. I aroldited the rear of the caps in rings once the tube was cut at 9mm (wanted a little gap) Filled and flatted down, primed, flatted down again and the paint/lacquered. Once dry, I fitted them into the wheels. Came out pretty good and looks OEM I think.