YouTube user OkiPanoki build a working NES inside an NES cartridge, because stuffing things inside of other things is not only awesome, but necessary. This was built using a Famicom clone — also called a “Nintendo on a chip” — which is technically illegal to sell but he found one at Goodwill for $6, and it would have run around $20 on Ebay. Finding the NES on a chip is the hardest step (besides the whole “being an electronics genius” thing); the rest of the parts are more widely available. It also uses an Arduino board, TI I/O chip, 72 pin connector, a couple ports, and a few other inexpensive bits and bobs.
Raise your tiny American flags and check out the NES stuffed inside an NES cartridge in the video below. The only way to make this more patriotic would be to play it while eating a turducken slathered in gas station nacho cheese. God bless America.