A 51mm “Star Grommet,” a name I believe was made up at the time of design. :)
The intended purpose is to be slit along the star shape, allowing the wire to pass through and offering some seal against dust or heat… like in a printing enclosure.
I included the STEP file if you need to change the diameter or panel thickness.
Print the “star” surface down.
This should be printed in TPU.
The author hasn't provided the model origin yet.