One Piece Front Bar

hey guys im currently planning to have a go at making a one piece front bar im just wondering if anyone on here has made one or can give me some pointers on how to do it best???
my plan was to fiber glass the plastic corners to the metal center piece the sand smooth and spary putty it and get it nice and smooth is this a good idea or is there a better way and just wondering what kind of prep i would have to do to get the metal and plastic to bond well

cheers rick!!!

there is a company that makes a fiberglass one piece front bumper. Corksport.com you wont find it on their site, but they have em. looks like this