Walnut allows you to visualise an artwork on your wall, before you buy it.
I designed, built and marketed Walnut with two friends. We registered it as a business and actually made some decent money from it.
That was in 2011. To this date it has the most accurate perspective artwork visulisation of any similar apps.
I partially built Walnut for the wrong reasons. I wanted to learn iOS dev and wanted to build an app. In reality, I didn't really care whether I was solving a problem worth solving, I just wanted to build an app (because that was a cool thing to do at the time).
I could write a lot on the things I learnt about launching a start-up, developing a business and managing clients, but I won't do that here. If we end up talking, I'm happy to go through it.
The most valuable lesson was that you should never enter into a venture with other people if you don't have the same goals in mind.
While I am proud of some of the early product validation work we did, including guerilla testing at art shows, we could have done a lot more to test whether people were willing to actually pay for the service.
We've disolved the business and retired the website, but the app is still live and you can download it from the app store.