You can't sanction the mutilation of a perfectly good NES cartridge... unless the game is of questionable entertainment quality. Take 1989's Championship Bowling. Even with its tantalising promise of four player action, I think we can find a better use for it. How about the best hard drive enclosure ever? Yes please.
A Reddit user by the name of "cheesey24" decided to put his DIY skills to the test and armed with a notebook HDD, a copy of Championship Bowling and a few improvised tools, he was able to come up with...
No, it's not a long-forgotten retro sim where you play the baron of a cardboard box empire, but a hard drive hidden away inside an NES cartridge. It's a little bulkier than the super-portable drives you can get these days, but it wins out massively on style points.
Just don't jam it inside an actual NES. Tears would be had, I think.