Our 7 year old decided to choose his own costume this year; a GEICO Money Stack costume. Of course, this was a costume that you could not buy in a store. It took a lot of planning to get this costume to look good as well as to fit well.
The first issue was making a 4ft long copy of a $5 bill. Many nationally-known Copy companies had issues with doing this due to counterfeiting regulations. (As if we could possibly hope to spend a 4ft-long $5 bill!) After the issues were sorted out, we found a place to do our copies. We also had to make it lightweight so that our 35lb son would be able to wear it. This was accomplished by using Styrofoam for about 95% of the costume.
My son also wanted to wear black clothing to camouflage his body in the darkness, while he was trick or treating. All of our neighbors could not believe how great he looked. When he returned home with his brothers, he told us that many people took his picture. We had fun making this Homemade GEICO Money Stack Costume and he had fun wearing it.