As an aside, the fact that I saw the paper on perfect pitch acquisition and turned it into a usable app within a few days is one of the things I love most about being a programmer. When a tool doesn't exist, you can just make it, and make it how you want it to be!
This goes for all kinds of making skills. My cargo bike doesn’t have blinkers, but it’s my main way of getting around. The cheap wireless blinkers you can get off of Amazon have all kinds of annoying problems (including silently running out of batteries so you don’t realize your blinkers don’t work!), so I got together a bunch of parts and wired up a full blinker system¹.
When some random part of a door in my house broke, I just designed a replacement with my 3D printer.
I’d also really like to be able to make or modify my own clothes, since I often have an idea for something I’d like to wear, but can’t find exactly the right thing anywhere.