Minnesotastan of the famous blog TYWKIWDBI found this image at /r/specializedtools, which is my new favorite subreddit. I could waste whole hours there.
But, instead, I'm going to tell you about these simple but amazing devices. They're called eye caps. Morticians use them to make sure that the eyes of dead bodies stay closed, which would make open casket funerals awkward. In her book, Stiff: The Curious Lives of Human Cadavers, Mary Roach explains:
The spurs work on the same principle as those steel spikes that threaten Severe Tire Damage on behalf of rental car companies: The eyelid will come down over an eye cap, but once closed, will not easily open back up.
You can buy them for your professional or recreational use (I'm not judging) here for about 17 cents a pair.