I have this.
http://www.amazon.com/Am...id=1330842984&sr=8-5I got a standard #9 stopper and ended up pushing it far enough in that it got stuck inside. It also didn't stop leaks when simply held upside down.
Can anyone recommend me a stopper that will both stop leaks, not fall in, and not be so large that it won't fit at all?
Also, I wasn't sure what material to get the stopper out of, and I wasn't sure it was if it would fit right so I didn't want to get anything expensive at first (just plain rubber, I covered it with a couple layers of medical-grade nitrile but it was still thin enough to fall in).
I wanted something with a wide range of chemical resistances in case I decided to use different acids/bases/solvents and I'm a tad overwhelmed by the varieties of materials.