The Wright Stuff
The Sparkfun site has this guest write up post about a marvellous, laser cut, Halloween costume. They go through the whole process of simplifying a 3D model and slicing it into something that can be cut on a laser. They even insert nodes into all the joints to help them stay together with friction.
Don't just wing it, start now and there is lots of time to get a costume sorted before the end of the month.