This is why I took up 3D printing three years ago. My home is 25 years old. Plastic switch covers and knobs break all the time. The problem is many of the broken items can't be replaced since they are no longer sold or are not sold separately.
My first project was a drain stem aligner for one of our bathroom sinks. It looks like a spoked wagon wheel with a hole through the hub to center the drain plug stem. The item was used on Newport Brass drain plugs. Our cleaning person pulled it out to clear out a drain and pitched it. It is a bad design and the aligner is no longer made. Rather than replace the whole drain assembly, I pulled one from another sink and reverse engineered it. I did a CAD drawing from my measurements and printed it. The new part works like the original.
My second project was switch covers for our range hood. Over the years, two out of the three switch covers disappeared. I reverse engineered the remaining one and made three new covers on my 3D printer.
Over the last three years, I have made a lot of replacement parts for all kinds of things. A cool retirement project. My kids send me requests all the time for replacement parts like drawer knobs and the like.