No matter where you're from or what you do for a living, thanks to the conveniences afforded to us by the internet, making money is no longer a constant and never-ending struggle. With the proverbial world at our fingertips, as long as you know how to tap into the vast amount of opportunities found in the digital ether of cyberspace, you can earn some extra income, even if you're in a tight bind.
This business is good for people who are both creative and practical. There are an infinite amount of design options for phone cases, but some will be more popular (and profitable) than others. A good business owner can both narrow down the choices, and predict trends to gain a market edge. Owners will also need some customer service and advertising experience as well.
I surprisingly get a lot of people asking to detail their car. I never intend to make a business of it, but I love doing it to my cars and people ask me to do it to theirs. All it takes is a cheap orbital buffer (mines a used craftsman) and a shop vac. I normally get easily $100 for a basic wash/wax/vac, or $200 to remove scratches and polish then wax the car.