This costume will not take you longer than 30 minutes. You will be a roll of toilet paper. People will laugh. It will cost you around $35.
Step 1: What You Need
Two packs of foam sheets, 24" x 96" x 1" They cost about $15 each.
1 black sharpie
1 Large safety pin
UPDATE: After wearing this costume for about 8 hours straight, I recommend forgoing the velcro and using one giant safety pin on the outer layer. The velcro was fine for just standing around, but when truly put through the paces, the velcro wasn't robust enough. I put a large safety pin through the outermost two layers and it worked all the rest of the night.