Ask HN: Those with money-making side projects,how did you come up with the idea?

New job, more stuff to do, so I got myself a 4K LG Monitor to extend my small Macbook screen.

I had set up my home office right on an interior balcony where I had lots of natural light.

That meant that the monitor brightness and contrast needed to be constantly adjusted to have the screen visible in sunlight and to not blind me when the clouds/night came.

If you ever used an external monitor, you know how cumbersome it is to adjust the brightness constantly using its physical buttons or touch controls. And macOS doesn't provide any way to change the brightness from the Macbook, unless you use something expensive like an Ultrafine or Studio Display.

So I started working on an app to automatically adjust the brightness based on the sun position in the sky.

I run CAD Class (https://www.cadclass.org) as well as a small 3D print farm selling custom clips and connectors for workshop equipment.

CAD Class was born out of my frustration with inadequate CAD learning resources online. When I was learning I had trouble finding a class that truly got me where I wanted to go (I wanted to develop and sell my own products). Classes I found were:

1 - Not comprehensive enough or just flat out boring 2 - Not supported by a community who could answer my questions in a reasonable timeframe in a way I understood 3 - Outdated due to software updates 4 - Lacking the right learning structure to truly advance my skillset

I built CAD Class to be the ultimate online learning resource. A kind of one-stop-shop for students learning CAD and wanting to build their dream projects.

For the print farm, I was simply scratching my own itch. I designed a few highly specific and hard to find adapters to solve a dust collection problem I was having. I realized that nobody had advertised adapters for specific equipment and that they were all generic and therefor hard to search for. The innovation here was not so much the product as it was the ease of searching for it.

Lastly, since it seems you're not sure what to make, I don't see any reason to force it. I'd suggest joining another small team or company, or simply taking a job that keeps you occupied until you come up with something you are genuinely excited about working on. I took a job with a community college teaching CAD, consulted with a few museums and startups, and wandered until I nailed down my idea. There's something to be said about keeping momentum.

It actually started as a Mac app 10 years ago and I choose to create a solitaire game because I had made a string of side-project that I didn't earn any money on, so I wanted to see if I could find a project that would actually generate some side-income.

I did it by scraping the Mac App Store so I could find apps that had a lot of downloads and bad reviews. I figured that if an app had a lot of downloads, but got bad reviews then I could create something better and there would be an audience for it. The app ended up making enough money that I've kept it as a side-hustle for all these years. I've written about how I picked the app here: https://www.indiehackers.com/post/how-i-grew-a-simple-solita....

Thanks a lot for this project! I love it, and will be using it from now on.

I thought that social networks like Twitter and Facebook would drive most of the sales, but it was actually the 800 person email list I'd built. From then I became obsessed with how to optimize email marketing. I hacked MailChimp to organize lists, give away incentives for opting in, and more. But it was all hacks. In early 2013 I decided to build an email marketing tool specifically for bloggers and content creators like me.

I made it really easy to give away free incentives (ebooks, sample chapters, etc) to get subscribers, pioneered a new writing interface for time-based email sequences, and made subscriber organization really easy. It stayed a side project for two years (hitting $2k MRR and then flatlining).

In 2015 I decided to double down and make it my full time venture. From there I focused on direct sales and concierge migrations (a fancy way to say I'd do the full switch for you for free). In 2015 we grew from $2k in MRR to $98k. Then in 2016 from $98k to $500k.

Today ConvertKit is at $33M in revenue and has a team of 68, but it all started as a side project!