This was done by a 5 year old so I do have some tidbits to share with you if you plan to make this a project for your child(ren). Most nail polish is not water soluble like so many craft items for kids. This may seem like an obvious point but with the chaos of the day, juggling more things than I should, I failed to remember that point or maybe I just didn't think about the things that could go wrong with craft project using nail polish. Now you are imagining the worse, right? :) Don't write off this project! It can be done. In my case my table and my floor could be clean using a little nail polish remover - there were little dots of nail polish everywhere. Just be sure to cover the table (work surface), maybe the floor and have your child wear a smock or old clothing that you don't mind staining. (We lost a shirt in the project but again, that was because of poor planning and lack of "imagining the worst" on my part.) And if you are an adult wanting to do this, maybe you don't have to worry about all the disaster prep. Just grab some nail polish colors and start decorating! A little creativity is good for the soul and a great stress relief.
At my house though, it was a kids craft. My daughter decorated two keys. She enjoyed the project and I have enjoyed the results. She got to use her creativity and I get to see her handiwork every time I use my key. The nail polish is holding up well. No chips at all. A Pinterest project success! :)