Fits snugly with one of these common humidity sensors that you can easily get on Amazon.

https://www.amazon.com/gp/product/B07GNMKYCZ

You will need to print with supports, see the attached gcode for preferred orientation. Be carful not to snap the tab off when you stick it on the Skadis board, it's fairly easy to do so unfortunately.

Edit: Updated print files with better tolerances to make attaching it to the Skadis easier and more durable