KB Adjustable sock loom(Still need to test it on other looms)
tapestry needle
scissors
White yarn (other colors for the inside of eye)
or small button.

About 5 cm(1.97inch) big.

I’m sure if you knit the eye on a other loom, just follow the pattern, when you need to decrease, decrease. To get the eye flat and round, it all about the decrease.
Let me know if you test the eye on a other loom, and if it worked.