Its a mount for the RaspberryPi Touchscreen Case by RonnyS.
You´ll nee M3 Inserts (like this https://www.amazon.de/gp/product/B08BCRZZS3/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1), M3 Screws and to assemble it also 2x T-Nuts for the Extrusions.
The author remixed this model.