The purpose of the intake is to help the GPU getting fresh air. I haven't done any benchmarking to prove it works, but the poject was fun.
The intake is mounted on the fan and the case. There are a few little screws that came with the case that should fit. It is quite a hassle to put it in place but for me it only took 5 minutes.
To print the intake on a prusa printer without support I had to cut the intake in two. On the photo you should see the seam.
The author hasn't provided the model origin yet.