#2 rubber stoppers from testtube\lab beakers fit in mtb bars nice.
I bought them in a education\science store.
Or if you're in school\lab :rolleyes: .

And those stores are more abundant than bike shops? :)

Closer to me, and bike store ones are plastic -I like using rubber.
I was using cork -but found out it is a disappearing resource.

I'm keeping the correct ODI bar ends for racing if ever.
Also the inside diameter of my Amoeba DH bars is tiny, the tube wall is 5mm.
They will not take conventional plugs =small corks\stoppers.

I use rhodedendron leaves myself.....

That's cheaper than the $1.48 I spent on 4 stoppers.

:D Champagne corks of course!