This is a pan/tilt or gimbal base for an Onyhen IR Pyroelectric Infrared (PIR) Motion sensor (https://www.amazon.com/gp/product/B07GJDJV63/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1).

I created this Thing for use with a Raspberry Pi Magic Mirror project. The Pi is mounted underneath a table, but I wanted to create a solution for mounting the sensor separately with some flexibility for getting the best motion detection coverage. It's dimensions are specific to this particular sensor module, but could easily be adapted to similar modules and projects.

The plate is press-fit into the base and should rotate easily inside it. Print two of the neck parts and hot glue them into the slots on the plate. My attempts at press fitting these failed, so there may be room for improvement here. Once the necks are in place, the head should slide pretty easily in between them and lock into the circular grooves on either side.

Finally, wire your module, and feed it backwards through the largest end hole and the wires through the smaller rear hole. Mount, aim and enjoy. My PIR modules press fit nicely, but your mileage may vary.