DIY Modular Wearable Hub Inspired by the Arc Reactor

I've long been fascinated by wearable electronics — and like many aspiring engineers, inspired by the Iron Man saga. This project brings those two passions together.

Introducing the ARC_platform: a concept for modular wearable electronics centered around a hub element visually inspired by Tony Stark’s Arc Reactor. The idea is simple — a centralized core that connects and coordinates multiple wearable devices. Maybe even... a full Iron Man suit?

The real power of the ARC approach is modularity. Instead of every wearable needing its own processor, power system, and charging cable, everything connects to a single hub.

Connections between the hub and other modules are made using male-to-male TRS audio cables (like shown in the picture above), the ARC_platform introduces a new standard way of using these connectors to ensure compatibility between modules. This standard is as follows: the sleeve of the connector will be used for ground, the tip for power and the ring will be connected to a pin on a microcontroller.

Instead of sewing the tech into a single shirt, the ARC hub uses a magnetic mount that attaches through fabric. That means any shirt (or anything really) can become an "ARC shirt" — just snap it on, and you're ready to go. This small change makes the hub vastly more versatile, wearable, and reusable in everyday life.

Example code, .stl files, compatible modules and more can found in the GitHub-repository: Helger2007/ARC_platform

Note: The most up-to-date files can be found in the repository above

Components

1. 1x 3D printed parts
2. 12x 3.5mm jack connectors (stereo)
3. I can't find the exact ones I used, but for example these (amazon.nl) should work. If you prefer insulated sockets this can be done, but the enclosure might need to be adapted.
4. 1x Velleman VMW100 development board
5. This board was replaced by the WMW100, but the newer version should work just as well (not tested, but appears to just be a rebrand). You can get it from the manufacturer here (velleman.eu).
6. 1x battery holder (or USB power bank)
7. There is a battery holder shipped with the VMW (same goes for the WMW), but this board also has integrated LiPo charging.
8. 6x small neodymium magnets, like these (amazon.nl).
9. 8mm diameter and 1mm thickness
10. Stripped, Solid-core Wire
11. Or insulated solid-core wire that you strip yourself. I've tested with wire from 0.5mm to 0.8mm in core diameter

Tools

1. Soldering iron
2. Soldering tin
3. Micro-USB cable (for flashing firmware, ships with the WMW)
4. Arduino IDE, can be installed here (arduino.cc).
5. 3D printer
6. One of the prints requires a special step during printing, which, to my knowledge, isn't offered anywhere they provide 3D printing services; thus, printing them yourself or at a local makerspace is recommended.
7. Permanent marker, paint, or any other way to clearly mark a metal part
8. Wire stripper or hobby knife

The top part of the housing should be printed upside-down, with supports on build plate enabled. This way the front of the hub is printed against the bed, which will be smoother.

The magnet holder can be printed with the slots facing up, since this part wont be visible.

The wall of the hub should be facing right-side up and could benefit from some support enforcers inside the holes for the serial and battery connectors. The holes for the jack-connectors should be printed without supports, they will get in the way when inserting the ground wire into the channel:

To connect all the jack-connectors to ground, there is a channel inside the hub-wall to accommodate a 0.8mm stripped wire. This wire has to be inserted during the printing process, we can do this by pausing the printer at the right layer. In PrusaSlicer this can be achieved by adding a color change to the .gcode while slicing, as seen in the pictures above.

I modeled the enclosure in Fusion 360 specifically for the VMW100, feel free to adapt the .f3d file below to fit your microcontroller of choice.

Before assembling the hub-wall, it is important to prepare the connectors in the correct way.

First, unscrew all the nuts from the connectors. Next, separate 2 out of 12 connectors and the same amount of nuts; these two will have a different function.

Start with the group of 10 connectors: these will be using their full potential and all 3 lanes of the stereo connector.

Every one of these connectors will be connected to a pin; to do this we have to bend the connector-pin for the middle lane up, as seen in the third picture.

The other 2 connectors will be connected to 3.3V and ground, respectively. Bend the pins accordingly and as seen in the 4th picture. Mark the 2 nuts to indicate that there is no pin connected on this connector and that they are only used for power.

Depending on the diameter of your internal wire, you can now either screw or press in the jack connectors and secure them with a nut.

Double-check whether the right pins are bent upwards with a multimeter; messing this up will almost definitely create a short circuit.

Lastly, be sure to install the connectors for ground and 3.3V in the right spots for them to connect to the respective pins on the board and use the marked nuts to secure them.

If you use a different board, this might be a different layout.

3.3V

Soldering the wire for 3.3V is pretty straightforward: the way the jack connectors are installed, the connector pin for 3.3V should be on the back of the hub. So it's just a matter of connecting them with a piece of wire. This wire can be insulated or stripped, but I chose to go with stripped.

Make sure to connect one end of the wire to the prong of the connector that links it to 3.3V on the board, as seen in the second picture.

Pins

All the other connections are soldered directly to the board, which can be pressed in from the front of the hub. The holes for the serial and battery connections, as well as the front/upward-facing connector pins, should line up with the connectors and the correct contact pads on the board.

For this step we simply use double-sided tape or your glue of choice (I prefer superglue) to fix the magnets in place. You can press-fit them first to check the if poles align.

Finally, we press-fit the outer magnet ring onto the hub wall and add the top cover to finish the build.

You have now finished building the ARC hub; time for some final tests using a simple example sketch.

Connect your hub to the Arduino IDE by plugging it in using the micro USB cable. Next, open the example sketch attached to this step (you can find more example sketches in the GitHub repository linked above) and change the variable (highlighted number in the screenshot) to the number of the pin you would like to test.

This sketch lights the first LED on the board according to the state of the chosen pin, this way we can check the solder connections per jack connector by shorting the pin-channel to the ground-channel.

You now have your very own ARC_platform hub.

You can program it to do whatever you want, like display LED animations, control other wearables and so much more.

Use the connectors for servos, sensors, or even more LEDs; it's all up to you.

I invite you to experiment, invent, and create on this new platform of modular (and standardized) wearable electronics.

This is my first ever fully public project and first intructable. Thank you for reading, let me know what you think!