ive got a big niko on my steyr. the sunshade if fitted would foul the barrel support. so i made one out of 70mm o/d black plastic drainpipe from B&Q (£3) and black tape with a cut out at the bottom. also angled the front so it protects more from overhead light.
you can't tell its a botch job untill you look closely
p.s i sprayed the inside with matt black to stop an intermittent slight reflection or you can line the inside with that matt black paper that artists/schools use.