I made this literally 20 minutes before we left for trick-or-treating - but it didn't turn out too shabby, I think. I made the back one longer because I didn't have enough long tubes, and I figured the tube would probably lose momentum on the way in, anyway.
Front: Toilet paper tube covered in foil, then red paint.
Back: Paper towel tube covered in foil, with a little red paint around the base
My method: I poured the paint on my hands and smeared it around with my fingers, which killed 2 birds with 1 stone: I got my shirt AND my hands bloody (presumably from clutching at my wound).
Sorry for the shabby photos - I had poor lighting. :)