"Here's looking at you, kid."

Ok, in general you only have two eyes. This might be sufficiant, but why not have some spares? Print your own eyes in your favourite colour.
And there is more - these eyes not only look good, but you can open them. Only a few rotations and you can place some candy inside as a spooky giveaway.

Printing is quite easy: Print everything with three walls, four tops & bottoms and 8% gyroid infill. Support is not needed. For a neat tumbling figure effect you can make the bottom half extra heavy by printing it with 20 tops & bottoms. Then the pupil will always face up.

After printing glue the iris and the pupil to the top half. Screw the thread in one of the halves and close the container by screwing the other half to it. For an optional reflex effect draw a single white dot on the iris. Just use white paint or a white permanent marker.

Disclaimer:
This work by blecheimer is licensed under a Standard Digital File License. It is for personal use only (e.g. printing, gifting, presenting, showing). All files and any prints of it must not be used commercially. Any form of charging money or collecting fees for this model is strictly forbidden.
Sharing, sub-licensing, selling, renting, hosting, transferring, distributing, adaptation or derivats in any form or format is prohibited. This includes remixes. Copying or hosting this model to other digital websites, online stores or cloud services in general is not allowed.