My mom was part of the rebel alliance and a traitor — NOT!
One year I went trick-or-treating as Darth Vader. My mom made the costume. She put together a black cape (sadly, my childhood wardrobe did not include capes), a black shirt, black pants, and black shoes. She drew a fancified, technological looking thing to serve as my chest plate, like James Ea--Darth's, but she attached it a piece of padding so that I could do my little kid moves without it chafing or getting it wrinkled and otherwise getting dorkafied.
For the helmet, she used extra-reinforced black construction paper. She took a large piece and rolled it into a conical shape, almost perfectly symmetrical, and fastened it with staples. She then cut a circular-shaped piece for the top, making it a little extra big so that she fold down the edges and fasten them to the inside of the top of the cone--so that it would be flush and wouldn't stick out past the cone and give me a most unDarth-like anchor head.
And yes, she did cut out eye holes, although I can't discount the untapped comic potential of going out as Darth Wonder. That reminds me, the helmet looked a little bit like the bucket that got stuck on Homer's head in the episode when Bart became a phony preacher. For my weapon of choice, I used a very cheap light saber knockoff that I borrowed from a friend.
Anyway, the entire ensemble couldn't have set her back more than 50 cents.
And when I went out, it seemed like every kid liked the costume but not as much as adults liked it. Some people who I knew stood right next to me trying to figure out who I was. I hope I was clever enough to breathe heavy and say things like "They must have hidden your brains in the escape pod" and "The force is weak in this one," but probably not.