Your concept is good but i don't have idea about what can be made out of old mining hardware. Mining hardware manufacturer such as bitmain have to think about recycling their old hardware, because they may have idea on how to recycle those old hardwares.
Thanks! Ya so far brainstorming ideas of what we can use them so for so far has been interesting. The structure of miners with heatsinks and fans is similar to LED grow lights so I made some out of an old s5 and old u3. You can see those on our project page. Just some basic ideas but definitely looking for more