To SXSW & Back — Mixfinity March '26 Recap

Last month, I traveled to SXSW music and tech and film festival to exhibit Mixfinity; hardened the mechanical design for real-world demos; and shipped the first firmware for customizable mixtapes with a new mixtape.json schema.

I exhibited at the Austin Hardware Meetup Garage Party on the Monday night during SXSW, attended a handful of speaker events and a few more off-site meetups. Several of us hardware folks also stayed after at the event to order more drinks and to "show and tell" our different products more closely, and generally the vibe at the event was a strong response and I'm happy I got to show the product off to some new fans in Texas.

Mechanical Updates

For the first two weeks of March, I was busy at the makerspace designing and 3D printing new Mixfinity tapes. The prototype tapes I had taken with me to CES were fragile and required careful handling, so I focused on making the design demo-ready for SXSW.

The biggest improvements I made were 1) the PCB carrier tray and 2) the new "button strip" that joins all five playback buttons together: Volume Up, Volume Down, Play/Pause, Previous Track, Next Track. For the prototype at CES in January, the buttons were each separately printed and held in place with a little retention ring reinforced with glue, and while good enough for my first demos, I needed to iterate. The new strip improves alignment, durability, and ease of assembly.

The button strip, circuit board, and E-ink displays all attach to the new PCB carrier tray. And then the top and bottom halves of the exterior shell fasten around the tray. This tray ensures that all the components like the buttons and the USB-C port land at the precise X/Y/Z positions for their cut-outs on the outer plastic shell.

And fully assembled, you get this cool green-blue Buzz Lightyear-themed slab.

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The product label on the back (product SKU MXT-01) and the imprint label on the spine (album name) are also new. I didn’t have enough lead time to source the production-quality metallized polyester labels I discussed in last month's recap in time for SXSW, so I made them myself. These were designed in Adobe Illustrator and printed on matte vinyl sticker paper and then cut with a Silhouette Studio vinyl cutter.

You can see the imprint labels through the clear jewel cases in this photo below:

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Firmware Updates

I shipped a couple new features in March.

mixtape.json. For all files loaded on to the Mixfinity tape USB storage, I formalized a JSON schema to populate the track listing and playback order. While in an ordinary album release, the MP3s will be burned onto the USB storage (and also onto a factory recovery partition), listeners are free to drag-and-drop their own MP3s and edit this mixtape.json file to change the playback ordering. The JSON format looks like this:

{
  "version": 1,
  "name": "Podcasts Vol. 1",
  "tracks": [
    {
      "title": "Elon Musk",
      "artist": "Various Artists",
      "filename": "01-elon-musk.mp3"
    },
    {
      "title": "Pale Blue Dot",
      "artist": "Various Artists",
      "filename": "02-pale-blue-dot.mp3"
    },
    {
      "title": "Cars",
      "artist": "Various Artists",
      "filename": "03-cars.mp3"
    }
  ]
}

This effectively turns Mixfinity into a programmable album format.

Screensavers. I also added screensavers. Previously, artwork was baked into the firmware. And now it’s fully user-replaceable over USB. The new firmware will load any JPEG saved to the paths screensaver-front.jpg and screensaver-back.jpg.

The firmware and user experience is super simple and that's kind of the point for an analog-inspired hardware product. It's basically ship-ready for making bespoke mixtapes for your friends and family at this point, so I've turned my focus to fundraising and marketing and the rest.

Month Ahead

Writing this March recap blog post on April 18th during my Disney spring break vacation, I already know a lot of what's been accomplished in April. I did form a company finally — more on this story in the next month's April retrospective recap. I've also started working on the Bluetooth pairing user experience. I'm implementing a couple strategies: automatically pair to the nearest AirPods or Bluetooth speaker with the strongest radio signal; and, a more conventional picker dialog on the E-ink screen. My goal is to make pairing feel invisible, with a picker dialog fallback when needed.

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