I think one of the aspects I like most about 3D printing is the ability for anyone to generate what I like to call a Very Specific Object, which is an item with a purpose so niche it's a near certainty no one but the author would ever have a use for it. Ergo, it's an item that by definition doesn't exist, or rather didn't until it was created for its bespoke purpose. And the point is that it does have a functional purpose, but the more obscure the better. The beauty is that we can create such things as we see fit.
I think I achieved nirvana with this, then, given that this model has garnered precisely zero downloads on Printables. Despite the fact that at least one or two punters inevitably download any damn fool thing I post there. Not even the scraper bots want this one.
https://www.printables.com/model/783183-ikea-nordkisa-drawer-stopper-clip
This is a clip-on end stop for the Ikea Nordkisa nightstand, in and of itself a specific enough object. It prevents the drawer from being pushed out the back, which is an aspect that while highly annoying has probably only had the chance to personally annoy a very, very small portion of the world's population.
I used 3d printing to make custom screw covers. Looks like that IKEA piece could use some, too!