Minifacturing
Along with Hanging Gardens, one of the two key elements to a true future. Not the cyberpunk kind, by the Star Trek kind.
Unfortunately, this is best represented in two of the best modern Lovecraftian horrors:
Mass Effect
Death Stranding
Minifacturing is the combination of several technologies:
3D Printing
Automated Machining
Robotic Manufacturing
These are all technologies that we have, but have never actually combined together into a system that could be run on the small scale. Like, say, going to the local gaming shop and 3D printing your Space Marines, already coloured. Have an interface that allows you to change the billion facets of it, add your own elements, combine elements from any models you have bought, and get your army.
This would have you buy the Minifacturing schematics/instructions, (structs?), from 40k, and pay for the time, energy, and local materials at the gaming shop.
And then extend this to appliances, firearms, motor vehicles.
The pressure-bearing parts of the firearm, which are legally the firearm itself, might not be able to be minifactured. The same thing with a car's chassis.
The benefit of this is not just being able to fully customize your car, but the ability to perpetually produce components for it. Availability of components is one of the biggest things limiting the life of more reliable automobiles.
But, this would require major automobile manufacturers to acknowledge that they are designers, and that they SHOULD not have direct control of the vehicle the moment it leaves their factory.
I'm looking at you, John Deere, but this is also what crippled the newspapers, and is destroying Hollywood. They refuse to adapt, to accept their place as producers, and not instruments for societal control.
Newspapers refused to move online, and when they finally did, we had a culture of not paying for news online. Because you couldn't. The internet is for sharing, and it took the Dotcom Bubble, (and a LOT of porn), for people to figure out how to run commercial businesses online.