Minimesh | Standalone fakeTec Messenger Node (Heltec V3 Now Supported!)

UPDATE (June 3, 2025):

• Added a Heltec LoRa32 V3 revision of the case.
  • This is untested! If you print one, please post a make - I would love to hear any and all feedback, especially if it needs work!

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I'm very excited to share my first major CAD project - the Minimesh!

The Minimesh case was designed to house components that I already had on hand with easy access to, with only 2 printed parts! Considering the components it uses are also rather cheap, it kind of turned into the perfect budget friendly build for anyone wanting a standalone communicator node with great battery life, freetext support, and a buzzer.

Hardware:

• 1x MakerFocus 3000mAh battery (or anything up to 65x36x10mm)
• 1x U.FL/IPEX to SMA pigtail, ideally 5cm
• 1x Assembled fakeTec node based on the nRF52 ProMicro & HT-RA62/RA-01SH (tested with lupusworax's v4 PCB)
  • Alternatively, 1x Heltec LoRa32 V3 board (untested)
• 1x 12mm diameter buzzer
• 1x M5Stack CardKB
• 1x M3x6x5 heat-set insert
• 1x M3x6 machine screw (pan or button head, not tested with countersunk, though it may work)
• 9x M2x6 self-tapping screws - 5 for the faceplate, 4 for the fakeTec PCB
• (Optional) 1.75mm clear filament - insert into the LED holes on the faceplate, and cut flush with the surface for an easy light guide

Important Assembly Notes:

Because of the DIY nature of the fakeTec, there is a lot of variance in terms of part tolerances. Minimesh was designed to take into account some vertical misalignment of the display, as well as display PCBs that might be a little bit larger, but I only had one on hand to test with.

This project also supports the Heltec LoRa32 V3, however the current revision of the case is untested and may need extra work, post-processing, or hot glue. You have been warned!

ProMicro Variations:

There are two versions of the main body, designed for two different ProMicro PCBs.

• If your ProMicro has the USB port level with the top of the PCB surface, print the Main Body V1 model. This is the case for most clones I have seen personally.
• If your ProMicro has a “mid-mount” USB port sunken down into the PCB surface, print the Main Body V1 (Lower USB) model. This would be necessary for the official nice!nano (untested) and several clones such as this one.

Soldering:

When assembling your fakeTec for this build, do not use the pin headers. Solder the Pro Micro flush with the fakeTec PCB - I achieved this by using some clipped diode legs through the holes, and bent in place while soldering. This can be done with a breadboard, too. 

As for the display, ensure that the screen is level and not rotated, and that it is as flush as possible with the Pro Micro. I suggest putting some kapton tape (or anything insulating) between the back of the display and the Pro Micro to avoid shorts. 

Notes on Wiring:

There's not nearly as much room inside of this thing as I would've liked there to be to account for the wires - much of that comes down to my inexperience with CAD stuff. However, there is enough room for everything if you're careful with your wire lengths.

For the CardKB, keep the wires together, and do not split the ribbon cable apart quite yet. Measure the length of wire you need to go from the CardKB to the SDA/SCL/3.3V/GND pins on the bottom of the fakeTec. To make things easy, after you cut the wires to the right length, solder these wires to the same pins the OLED display uses.  ** Yellow to SDA, white to SCL/SCK, red to 3.3V, black to GND. **

Ensure the buzzer wires are fairly short and do not go much further than necessary for the buzzer to fit the faceplate. Do leave a bit of slack to ensure you can attach it to the faceplate when everything is installed inside the main body.

The SMA cable might give you some trouble. If you have a thicker and less flexible cable, like I do, you'll want to get the wire as close to the CardKB side wall as possible and coil it there to make sure it doesn't collide with the buzzer and pop out of the LoRa module when assembled. If you have a thin and flexible cable like what comes with the Heltec, or what the black/grey wires on Amazon typically are, you won't have much trouble routing it. Check how the buzzer slot on the faceplate sits when assembled, and route around it. Future revisions may have a slot to help route the trickier wires.

Notes on Configuration:

Depending on your hardware, you may have to change the screen orientation in the Meshtastic app, under the radio settings panel. This is especially true if you're using the Heltec V3, which will definitely display upside down. 

For the CardKB to work, make sure the canned message module is enabled. You may need to reset the node once or twice for it to pick it up. You don't need to specify any specific input device, as the firmware will automatically detect it!

Happy messaging!

Please feel free to shoot me a message if you have any questions! You can find some of my contact information on https://5panel.dance or message me/leave a comment here on Printables.

Print Suggestions:

• No supports needed for either piece
• Print the faceplate face down
• 25-30% infill on the main body, with extra walls (5-6) for strength
• 50% infill on the faceplate (optional, worked well for me)