Thank you, 77 Maple, your idea of using a coffee thermos is brilliant! I have a stainless steel Coleman coffee thermos that I'm not using. It is 9" high with an opening diameter of 1.6 inches at the top and a diameter of 2.5 inches wide at the bottom. It would make a good stable place to put the hydrometer in between tests, and it would be easy to wash afterwards. Here's Amazon's picture of it:
The utensil drying rack that I ordered a few hours ago from Amazon is 3" wide in diameter and 5" high. I think that it would also work. It's wider, which could cause a problem, but it's also less high, so it could be easier to place the hydrometer in it without breaking. Also, with it hanging from the inside of a pot or sink, there's less chance of me knocking it over with the hydrometer inside. Here's Amazon's picture of it:
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