A simple holder for those cheap round hygrometers.
These are the ones I have, but the same model is available in lots of places: https://www.aliexpress.com/item/High-1pcs-Mini-LCD-Digital-Thermometer-Hygrometer-Fridge-Freezer-Tester-Temperature-Humidity-Meter-Detector/32824574308.html?spm=a2g0s.9042311.0.0.610a4c4d6dJOqA
UPDATE: Depending on your printer and/or slight variations in product diameter, it might be a quite tight fit. User TheGooNie adressed this in his remix: https://www.thingiverse.com/thing:3080643
| hygrometer_holder_v5.stl | 21.4KB |
