i know what you mean but im not sure,i have seen like these circle mats of hard plastic,i dont remember what they were for exactly somthing for a slope maybe. if you put a piece of somthing like that around the head it might work for a while,other than that one of the tools for planting bulbs,its shaped like a cone and you can push it over the head to make a nice circle around the head. im sure there is somthing somwhere though.