I've been 3D printing accessories for the Volkswagen ID. Buzz since July. I started by modeling and printing a couple of things that I wanted, then added a couple of items that other owners have talked about on various subreddits and Facebook groups. I'm now moving about $750 worth of items a month. http://buzzprintco.etsy.com

I designed a pocket music instrument. I partnered with a company in China called Seeedstudio, they do the manufacturing, shipping, customer handling, etc. and I receive royalties on each sale. I varies from month to month, but above the 500$/month on 2025 :)

I love to be able to focus on the design and not the practicalities of selling a hardware product!

https://minichord.com/

https://unrav.io . Lets users reshape any article, paper, or video into the form that actually helps them think, mind-maps, summaries, podcasts, or interactive Q&A. Launched as part of the Bolt.new hackathon in August and growing steadily. Going from a 100% vibe coded web app to a full production system has been quite a ride!

I've got 2 that are kind of intermingled. Each averages a little over $500/mo on their own though.

Sportsbook API (https://sportsbookapi.com/) - A single API to get odds data from a number of US Sportsbooks

Odds Assist Pro (http://pro.oddsassist.com/) - An odds scanner tool that shows both current odds and things like arbitrage, plus ev, middles. This actually started as just a UI for me to quickly do sanity checks on the API data and eventually grew into a full site. The site is on a subdomain of a site my business partner had built long before we met, so it's kind of positioned as the plus version of that site.

API revenue is really stable and has been pretty consistent slow growth. Pro's revenue is all over the place since it's almost all referrals and promos with big spikes around major sporting events. Probably averages at least $500/mo if you look at the entire year.

kitecourier.com - the end-to-end certified mail platform that makes sending legal notices as easy as sending email.

Revenue is very spiky. Some months ~$10k, some ~$100.

Inspired by this Patrick McKenzie thread: https://news.ycombinator.com/item?id=7135833

Certified mail is weirdly powerful leverage. I decided to productize that.

I’m making around ~$600 MRR with Mentorbook.

It’s a tool that turns long-form content (PDFs, docs, YouTube videos) into structured, personalized courses based on how you want to learn.

I built it initially for myself — I consume a lot of content but struggled to turn it into a system I could actually finish and retain.

Early users came mostly from Twitter. Pricing is intentionally low ($9.9/mo), so it’s more of a slow, steady project than a high-growth one.

Still early, but I’ve learned a lot about what people are actually willing to pay for.

https://www.mentorbook.ai

I make https://universymbols.com and it’s still new, but off to a good start. It can create/restyle feature icons to expand an app’s icon set.

It supports SF Symbols, Material Symbols, and a bunch of open source styles, but I’m adding the ability to make a private custom style target.

My portfolio of iOS apps ends up at an average of $500/mo.

Most are older, still functional but rarely updated. A few of the newer ones include:

https://daylightgoals.com - Time in daylight tracker, using Apple Watch/HealthKit as the data source.

https://airlauncher.app - App launcher for visionOS - was much bigger last year before Apple added the ability to organize your apps.

https://itunes.apple.com/us/app/ibuzz/id304684758?ls=1&mt=8 - iBuzz - I built this app in a day 15 years ago, it still makes about $100/mo from ads and removing ads. Just a simple buzzer soundboard app.

Sadly not $500/mo, but I do get a few sales on https://dailychinesestories.com each month. It's as simple as it sounds - a story in Chinese at your HSK level for your preferred themes once a day.

I run drawcharts[1], which is a tool to help you build good looking hand-drawn style charts. It is not very expensive so I am currently making around 500 a year from it.

Also, as someone who likes to go to conferences and meet and connect with people, I found it hard connecting to 50 people at a conference on Linkedin and then reaching back out to them. So I build LinkedMemo[2] which is a CRM on "top" of Linkedin. You scan a profile, the profile is automatically saved and enriched in the CRM with a quick note.

[1]: https://drawcharts.xyz [2]: https://linkedmemo.com