Butter-Passing Robot
When the Smith family was too wrapped up in an argument over the breakfast table to pass Rick the butter, he put together a little robot to travel across the table, grab the butter, and bring it back to him.
On paper, it might not seem like a robot whose sole purpose is to pass butter is all that impressive. But you have to bear in mind that the robot became sentient, grappled with the soul-crushing philosophical revelation that there was no deeper meaning to its life than passing butter to people, and it only took Rick a few short seconds to whip it up.
Time Freezer
Having the ability to freeze time would be awesome. If you were getting too stressed at work or you wanted a few more hours in bed or you wanted to stroll around town without any crowds, you could just freeze time. And Rick’s time-freezing device doesn’t come with any nasty side effects like the one Christopher Walken gives to Adam Sandler in the movie Click. It doesn’t start skipping everything you’ve ever skipped before and it wasn’t created by the Angel of Death and it doesn’t have a weird DVD menu. Well, there is the side effect of ripping open the space-time continuum, but that only happens if you leave time frozen for too long.
Dark Matter
Dark matter is the fuel that allows for faster space travel. It proves to be such a lucrative invention that a whole race of aliens abducted Rick – and Jerry, accidentally – and put him in a simulation of his home with simulations of his family to get him to reveal the formula for it. In the end, he didn’t fall for any of their simulations, providing the episode with yet another plot twist (the writers didn’t call it “M. Night Shaym-Aliens!” for nothing) as Rick hums along to “Baker Street” and the formula he gave the Zigerions blows up their mothership.
Interdimensional Cable TV Box
This invention is so great that the writers of Rick and Morty squeezed two whole episodes out of it. In the first season, “Rixty Minutes” introduced us to an alternate reality in which Jerry is a movie star, a version of Game of Thrones where Tyrion is mocked for being taller than everyone else, and an appliance salesman named Ants-in-My-Eyes Johnson. In the second season, “Interdimensional Cable 2: Tempting Fate” showed us conjoined aliens who host rivaling TV shows, a game show that teleports random people into dangerous situations, and an action movie about a dystopian future populated with clones of Jan Michael Vincent.
Portal Gun
Not only is Rick’s portal gun his greatest invention, he also insinuates it’s his favorite one. It’s certainly the one he uses the most. Frankly, the ability to shoot a squiggly green circle anywhere in the world, step into it, and come out in an entirely different dimension in the multiverse is remarkable. It’ll almost definitely never exist in the real world for as long as the human race is around, because the technology behind it is completely unrealistic, but it’s believable in the context of the show, since Rick is depicted as the smartest being in the universe and it stands to reason that if anyone could create a portal gun, it would be someone of that description.