Prebuilt head trackers available here: https://medlin-drone-store.myshopify.com/products/pre-built-head-tracker
This is a case and mount for an Arduino based Open-Source Head Tracker. This is the the version two based off a different design. There are mount designs for both Fat Shark and DJI, as well as a universal mount.
Files on Thingiverse: https://www.thingiverse.com/thing:4980301