The 3-to-3 Connector: Mount ANYTHING to your Action Camera (for free!)

GoPro and similar action camera makers have great mounting systems, but by design, they can limit what exactly you can connect together. What if you want to connect a camera to another camera, or a camera to a light, or a camera to a…. Whatever you want? In this article, I provide a simple little 3D printed part that will fill that void and let you connect anything to anything within the Action Camera mounting systems!

The 2-to-3 Mounting System in Action Cameras

Anyone familiar with GoPro or similar style action cameras will recognize their iconic mounting system.

Simple but still robust, it uses a mesh of two and three plastic posts (or “fingers” as some call them) with a screw through them to provide clamping force. The system can be chained almost infinitely so that you can always mount your camera EXACTLY where you want it.

The 2-3 post mounting system seen in GoPro’s “ Grab Bag ” of mounts.

The 2-3 post mounting system seen in GoPro’s “Grab Bag” of mounts.

This system is so proven, hundreds of competing companies and accessory makers have copied the original GoPro design for their own cameras systems and more. It’s tried and true, and done correctly, it’s extremely reliable… But it can’t do everything.

The Intended “flaw”

One purposeful design element of the mounting system is that all mount-side pieces have 3 posts on them, and all camera side pieces have 2 posts on them. It’s a fundamental element of their function, but it also limits what they can do.

For example, the Karma Grip has a mounting ring that will allow you to attach it to a mount on a helmet, backpack strap, etc… but what if you wanted to attach a microphone, light, or even another camera to the Karma Grip?

Because both feature “camera side” mounting posts, there’s no way to secure them together.

2 posts + 2 posts = No mounting

2 posts + 2 posts = No mounting

GoPro doesn’t make a connector to do this, so one “quick and dirty” way around this is to take two connectors, saw them in half, and then glue them back together opposite rotation from each other to create a “3-to-3” connector.


This will allow you to fit into both the Karma Grip side AND the camera housing side.


While functional, this isn’t particularly elegant, and depending on your DIY/Glue skills, you could be risking losing a camera. I occasionally do camera comparison tests, and while these little mounts are useful to me, they take a bit of time to make and set up (epoxy cure times, etc). So, I opened up some CAD software and decided to make a few that I could 3D print instead.

CAD Files (free!) and Printing


You can download and use this file, for free, off of my thingiverse page:

Personally, I used this PETG for the prints. PLA is a little to brittle/rigid, and Nylon or Polycarbonate can be a little more difficult to print. I also used my printer’s default PETG settings, but I added supports , just so my circles wouldn’t slump or slouch. You may need to try a few things to see what settings will work best for you.


Print time was around 1hr on my Prusa i3 Mk3, and the results were exactly what I was looking for.



Now, you’ll notice I’m using an “acorn nut” (two, actually) in this part. You can pull these out of old connectors if you have them sitting around. Simply take one of the thumbscrews that normally get threaded into them, and instead of threading it in, push on it as hard as you can. It should force the acorn nut out of its hole, and you can then re-use it!

If you don’t have any spare connectors around, you can get a back of acorn nuts for a few bucks at your local hardware store, or even on amazon if you’re feeling particularly lazy. They’re M5x0.8 cap nuts. If you’re feeling particularly frivolous, you can get a couple murdered out black ones, too.

Either way, once you’ve pressed these into the new part's sockets (you can add a bit of superglue to keep them there, if you’d like) you can begin to connect things you couldn’t connect previously with the same mounting system, like attaching a camera to the Karma Grip for a side-by-side (or top and bottom?) comparison!

Expanding the system

If you want to compare 3 cameras, you can pick up this cheap “splitter” to add 2 cameras to the system.


From there, your possibilities are virtually endless! Just… don’t get carried away…


BONUS ROUND: Mount any non-action camera item to any non-action camera item!

Have you ever had one of those face-palm moments where you finished a project only to realize you did the entire thing backwards? Well, I started this one out that way, and instead of creating a 3-to-3 post connector, I made a 2-to-2 post connector… Which is “good” for attaching mounts to mounts.

At first, I couldn’t see any possible use for this, but I’m sure you could get creative with mounting an object with a double-sided adhesive mount, or something similar. What would you use this for?

Until then, let me know if anyone needs a hammer-to-ballcap mount…


EDIT: Looks like some do. Here you go!

Did this article help you? Is there something else you’d like to see me write about? For any questions or ideas, post in the comments section below, or make a post on the GoPro subreddit-

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