A sink stopper

A sink stopper. A minor thing really. But I lost mine.

It was Italian. A work of beauty that had a perfect union with the sink hole. After many an aftermarket stoppers were summarily rejected by the prudish Italian sink hole for being too big, too small, or simply mismatched on their interference plane I set on a quest to design a "perfect" sink stopper.

Unfortunately, there are no compendiums or seminal anthologies on sink stoppers. No "Sink Stopper Research Bulletin". No "Sink Stoppers 6th Edition" for $389 + S&H published by Addison Wesley. No. Zilch.

This is like Sushi - family secrets of sink stopper designs. I am on my own.

3 courageous attempts it took to conquer the stopper mountain. It wasn't easy.

Attempt 1: A "plug" with knob. Left most stopper in the picture.
Easy to use. Since sink hole isn't 100% round - it doesn't seal nor stay put.
Worse, it is hollow so it floats. It seems sink stoppers are supposed to stay at the bottom of the sink. I suppose I c