I had the air turbine idea in 8th grade! Once that was debunked, then I proposed adding a ‘floor’ of turbines to high rise buildings so they could generate their own electricity. To bad it wound make the buildings fall down. Lol…

I did see an actual prototype product at a trade show which put little turbines in your water pipes and to generate electricity for you own home.

I figured if it ever caught on then municipalities would ban them as they would be using more energy to pressurize the pipes properly.

I’ve seen a business like this. They make custom cards and etch cool designs on them. Marketed to rich people who think that having a black card isn’t exclusive enough.