Struggling to come up with an idea for a Halloween costume? We’ve got you covered. Some of rock and metal’s most legendary artists are very distinguishable, and they make for great Halloween costumes.For starters, you’re going to need a lot of black clothing, if you don’t already own it. Throw some leather and some studs in there, maybe a bit of lace. Next is makeup — a few of these artists wear corpse paint while…