Blades on the wheels, like for a windmill? I thought about it but the wheels are plastic (+no bearings) so there's no good way to attach anything. In theory you could cast new wheels (which are gears) out of something else but that's beyond my capabilities at this point.
What I was really thinking of when I started this was Norm's swing generator. He's got a neat bike-based setup (last I checked) but maybe a converted reel mower would work too....maybe better, maybe not.
Ideally, I'd like to keep it fairly broad though; push/pull and it generates some power. What happens next should depend on what attachment is hooked up.
The weedwhacker attachment is kind of obvious. Despite having grazing animals and a small tractor with a brush hog, there's still weeds in places I can't get to easily. I don't like carrying the weedwhacker we've got now (tortured spine), plus it's an over-polluting 2 stroke. If I can make a human-powered whacker with wheels...for a total of $25...heck yeah, I gotta give that a shot.
I might be able to make an edger too. And an attachment with a battery, lights and small inverter for camping.
I dunno, I just figured it was past time to "make electricity from scratch" so I put in a few hours and that's what came out...a working prototype. Now I just need to get the nut for my treadmill motor so I can get that hooked up instead. take it easy