I printed out and really liked these spool holders for making a filament storage box from an Ikea 22 L/6 gallon SAMLA container (part number 694.408.22). However, there wasn't a good place to mount a humidity sensor inside. Partly inspired by one of the comments on the spool holder listing, I designed a couple sensor holders that work with EWPJDK hygrometers available on Amazon. They insert into the junction between the spool holders.

I started out with a design that has the sensor display vertical. However, that made it difficult to view the LCD screen from above, like when the box is on or close to the ground. I then produced an angled design that is much easier to see when viewed from above. Both in-box brackets leave room for a layer of desiccant beads underneath the curved notches that insert into the spool holder. I had leftover sensors so designed a bracket for use on a tabletop. I also made a tool for removing the sensors from the brackets.

Only the in-box sensor brackets need supports. The desktop version can be printed without supports. Though not in the supplied print profile, I slowed down the outer layer speed when printing to give a more even surface texture. The Autodesk Fusion 360 file is included to allow easy modification.