As you know i love making small things. I make thing until i can't see them any more ,then use a microscope to even beat the record. So here is my one of the worlds smallest paper plane and mostly on instructables too. It is fully functional and could fly like a normal plane but covers small surface area. The plane is made out of 0.5 cm x 0.5 cm paper and then glues with super glue. It was custom designed and for sale as a collectible. I made about 5 of them for over a month or so, doing the designing and testing and then the final build. Hopefully i will someday make a instructables for it, but until then its for commercial sale.
It would be sold for around $10-20