How would you make a giant headed costume?

I would go to the fabric store and get a costume pattern. It is usually in the back of the pattern books. Then to make the head, use wire to make the circle like head, or maybe those large plastic ties, something safe but bendable. To make a real large one, use a hoola-hoop. I am a sewer and could use a lot of things. For a round head, use a can, those large popcorn cans, you could cut a face out, but naturally cover it so it is safe. If you need more help, let me know. Naturally, use the fabric of your choice. Painted paper plates are sometimes used for hands or feet, even faces. Good luck.