Never Miss a Print Failure Again with This $6 DIY Monitor

When a 3D print goes bad, it can go really bad. In the vast majority of cases, a bad print just results in a pile of wasted filament and lost time. But in the worst cases, 3D printers have even been known to catch fire. That’s not anybody’s idea of a good time, so people who do a lot of 3D printing can get pretty serious about their monitoring systems.

GitHub user Keralots does a lot of printing on Bambu Lab printers, and decided to make a DIY monitor to keep an eye on them remotely. The only hardware required is an ESP32-S3 Super Mini development board and a 1.54-inch 240×240 color TFT display, which come in at around $6 total. The enclosure for the device is — of course — 3D-printed.

What makes this project so interesting isn’t just its low cost, but how much functionality is packed into such a small footprint. The device connects to Bambu Lab printers using MQTT over TLS, allowing it to display a real-time dashboard with detailed information like nozzle and bed temperatures, fan speeds, print progress, and estimated time remaining. A set of smooth, anti-aliased arc gauges and animations give the tiny screen a surprisingly polished, almost commercial feel.

The monitor supports both direct LAN connections and cloud-based access. For printers that allow local control, it connects straight to the machine’s MQTT broker. For cloud-only models, it securely authenticates using an access token, without ever storing user credentials. This flexibility makes it compatible with the entire Bambu lineup while accommodating different network setups and user preferences.

Handling TLS connections on a microcontroller with limited memory is no small feat, especially when each secure connection can consume tens of kilobytes of RAM. The firmware carefully manages these constraints, ensuring that cloud requests and MQTT sessions don’t overlap. Large JSON payloads from the printer — sometimes up to 20 KB — are filtered and parsed efficiently to extract only the necessary data.

The device also includes a built-in web configuration portal. Users can connect to a temporary Wi-Fi hotspot on first boot, enter their network and printer details, and be up and running in minutes. Features like multi-printer monitoring, automatic display rotation, and configurable power-saving modes add further versatility.

For a few dollars and a bit of setup, makers can gain real-time insight into their prints — and perhaps a little extra peace of mind. If you’d like to build your own, step-by-step instructions and source code are available on GitHub.