Xiaomi LYWSD03MMC Stevenson Screen

I purchased a bunch of Xiaomi LYWSD03MMC temperature and humidity sensors for use around the house. They are cheap and work very well. I re-flashed mine with some open firmware and have been using them very successfully with Home Assistant via ESPHome.

I wanted to record the exterior temperature and humidity with the same Xiaomi sensor and this design is the result. It's a Stevenson screen that will allow free flow of air for temperature / humidity measurement. I wanted to make the design printable with no supports and to snugly fit the sensor.

There are 4 parts to be printed for this build. Main housing, base, sensor cradle and hanging hook. Everything push fits together except the hanging hook which is glued on. The top, base and hanging hook are printed with no supports. Supports are used for the sensor cradle.

As the assembly will be located outside, I used PTEG with a 0.2mm layer height.

For the OpenSCAD script, it's fully customisable and it can be adjusted to make other size Stevenson screen enclosures. I had fun making the script and it would be great if someone gets some further use out of it.

Update V1.5 - June 2023

The 1st version of the file had some issues as pointed out in the comments by @trvrnrth_88122. I have fixed the issues and made the sensor cradle better / stronger.

Also I was asked to make a version with a window to see the temperature sensor. This is also in the new V1.5 version

For the windowed version I cut a PET bottle up to make the window. It slots into the bottom and there are two small holes to poke/ glue a small bit of 1.75mm filament to retain the window and prevent it falling out. Depending on how well your priter does bridges, you may need supports.