Two years ago I open sourced my DIY CNC machine, which cost me £2,655.80 and 9 months of my spare time. The Fusion 360 project, the drawings, the bill of materials, the STLs, the wiring diagrams and the Mach3 profile, all for free.
People ask why I didn't sell the plans... the answer is simple. Selling the plans would have defeated the whole point of the project, shutting out the very people I built it for.
My goal was to build a capable, sturdy machine for as little money as possible. Industrial-grade larger footprint machines are well out of reach for most hobbyists and small woodworking businesses. With a few minor trade-offs, you can build my machine for a fraction of the price, with nothing more than basic workshop tools.
10,000+ downloads later, people all over the world send me photos of the machine I designed, now fully built and operational in their own workshops.
That's what I love about open source. It's for people. Nobody needs permission or a subscription to build their own tools. You can repair them, upgrade them, and write your own software, because you know them inside and out.
This fills me with joy like nothing else.