Personally? I built a heavy duty portable hard drive shredder than can shred a drive down to 1mm pieces in 60 seconds. Overall I sunk about $300k into the business and probably made back maybe $100k. I think we're 10 years ahead of the market, at least in Australia. But, it had huge impact on how I think about business, the customer, and how to pair the two instead of building awesome solutions no one needs (yet)
