This costume took many hours to make but with determination it is quite feasible. Materials you will need include: papier-mache, EVA foam(home depot), pleather white fabric and vinyl green (both at JoAnns fabric), platform shoes, a chest porector such as motocross or lacrosse, and lots of duct tape (purple, white, and orange)
Here is a link to see him live in action:
Step 1: Chest/ Legs/body
Cut out a front and back portion using a pepakura(google pepakura) guide on the internet and glue together to create and outer chest shell. Typically a hot glue gun works best. After you let it dry, cut the white pleather fabric to streak evenly and crisp along the eva foam. Cut out another strip of eva foam and cover it with the green vinyl so that it is proportional and placed on the white pleather chest. Continue this process by making an individual shaped speedo, two thigh and ankles. After finished, attach the white pleather and vinyl green where you see fit.
Step 2: Head
with lots of papier-mache begin to sculpt a face proportional to the body. Make sure to hollow it out so that you can place a bike helmet inside and be able to wear as a mask. Obviously, everyone will sculpt differently. The key is to focus on doing your best to making the head as close to resembling buzz's as possible. Be sure to open the mouth as well so that you can easily see!
Step 3: Hands
Use crutches or long boards as a base to develop hands that are proportional to the giant buzz. Cut up dowel into joint pieces and create lifelike hands.
Step 4: Assemble
make sure each piece is removable so that you can move around more easily. Have fun. I know it sounds complex, but honestly it is just a lot of repetition and good ole labor!