I needed something that'd fit nicely in their little shoebox tubs. So what I did is, I used round glass shotglasses, set inside a scoop from iced tea mix. I cut off the tab on the scoop and made sure there were no sharp edges there. Then I merely filled the shotglass a little more than halfway and put it into the scoop, for some more support as the glasses are topheavy. Presto! None of the hatchlings that I used this for (5) tipped their water overnight.
I used some of the square-edged glass shotglasses for the others and no one tipped those either.
Just a tip!