I had a Marine buddy tell me how to build a guilly suit once. Get some camo netting, fishing line, burlap sacks, and dyes colors of your choice.
Cut camo netting in a rough pattern for hood, shirt and pants. use the fishing line to "sew" (tie) the netting together. Cut the burlap into strips and dye to suit your needs. Then tie the burlap strips onto the patterns you've made. He stated for better effect, it is better to shred or unravel the burlap, after you have tied it on, to give it the "hairy look."
I have seen some suits that were not shredded and some that were. What ever you like best. Should be easy to find a source for these materials.