At the heart of Pebble is a simple recording interface that I designed specifically for the device.

The main screen has a large recording button with a timer displayed on it. When the button is pressed, Pebble starts recording through the built-in microphone, and the timer begins counting so you can see exactly how long you've been recording.

Press the button again, and the recording stops. The audio file is then saved directly to the SD card.

But I also wanted an easy way to access the recordings without having to remove the SD card every time. Since the UniHiker M10 has Wi-Fi connectivity, Pebble can connect to the local network and host its own web interface.

The device displays its local IP address directly on the UI. Enter that IP address into a browser on another device connected to the same network, and you'll be taken to the Pebble web app.

The web app lists all the recordings stored on the SD card, and from there you can play them directly in the browser or download the audio files.

So, all the recordings stay on the SD card, while the web interface simply provides a convenient way to access and manage them over the local network.

DESIGN PROCESS

For the design, I wanted to make an enclosure that really stands out from traditional electronics enclosures. I wanted something organic and natural rather than perfectly symmetrical and boxy.

The first thing that came to mind was a stone or pebble. I really like the irregular, curved forms you find in natural stones, so I picked up a couple of stones from a nearby riverbank and started studying their shapes.

I used them as references and sketched a few forms of my own, experimenting with different curves, proportions, and silhouettes.

After a bit of tinkering with the shapes and drawings, I eventually arrived at the form I was looking for, a simple, organic shape that felt natural enough to pass as a stone while still giving me enough space to fit all the electronics inside.

3D MODEL

Once I had the form I was looking for, I imported my drawing into Fusion 360 and used it as a reference to turn the sketch into a proper CAD model.

From there, I shelled out the enclosure and split it into two halves. I then started fitting everything inside, starting with the UniHiker board, then my custom power circuit, and the lithium cell.

A lot of the work here was making sure all the components fit neatly while still keeping the original stone-like form.

After going through the usual engineering and iteration process, I ended up with a very minimal enclosure that still looks and feels like a stone, rather than a traditional electronics enclosure.

I also wanted to make sure the important ports and controls were still easily accessible without taking the enclosure apart.

On the back of Pebble, I added a small opening that gives direct access to the microSD card. This allows the card to be removed from its holder whenever I need to transfer or manage the recordings.

The USB Type-C port is positioned on the bottom of the enclosure and is used for charging the device. I also placed the power button on the bottom, keeping the controls tucked away while still making them easy to reach when needed.

This keeps the overall stone-like appearance clean while still providing access to everything needed to use and maintain the device.

3D PRINTED PARTS

Once the model was finalized, I exported the mesh files and moved on to printing both halves of the enclosure.

I printed the top and bottom parts using Hyper Grey PLA with a 0.4 mm nozzle, 0.2 mm layer height, and 25% gyroid infill. I used tree supports only where they were needed, mainly on the inside of the enclosure.

Both parts were printed with the bottom side facing the build plate. This meant the outer surfaces were facing upward, giving me a much cleaner finish on the visible top layers.

For the supports, I used a 0.3 mm Z-distance and kept four layers between the support and the actual part. This gave the supports enough...