a few ways of doing it ..........
If your rod is made of fiberglass , thats what you should build one with .
If its metal , you can hand form one from flat 16 - 18 guage sheet metal, or look into speed shops like Jegs , as they have pre made ones , make sure you get a metal one to weld it in solid for strength and safety or you could go to salvage yards and cut one out of a junker thats close and fit it and weld it in .

not real hard just some fitting to get it right .