Hell the welding looks like the easy part to me but the fabricating whatnot looks like a *****, unless you have the proper tools of course. Which I dont have....

Im not sure of an online guide but its always helped me to plan out any build using cardboard and tape. Just cut to fit and use the peices as a template for making your actual parts. Just make sure you get the right radius for both sides of the tube fender. Leave that to a shop IMO.