I've known several older people who used a teacup and the palm of their hand to measure. That's what they learned growing up, watching their mothers cook.
My first ex's Aunt Gert was one of them. She made what they call "cat's head" biscuits, because they were that big. They made great ham sandwiches. Her husband, who grew up on the bayou around Gonzales, La, found her picking cotton in southern Miss'ippi. She was 13, and he was in his early 20's. He bought her her first baby doll and her first pair of shoes.
She was a wonderful person, and a big woman. When my then husband, big tough football player that he thought he was, started getting mean with me in front of her one day, she grabbed him in a bear hug, picked him up off the floor and squeezed the devil out of him, all the while saying, "You quit bein' mean to that girl!"
And she wouldn't let him down till he promised!
The other was my second ex's Aunt Lily. She was was a tiny little woman who looked like a dried apple doll, and made an old fashioned cornbread with no flour and no eggs...did require buttermilk, which was why I learned to make my own.
She also made some fine chicken and dumplings, and always swore you needed a good, fat country hen to make them good.
Her cornbread tasted gritty to me, but I learned to make it for my ex and his family, and I also learned how to make the dumplings (rolled, like noodles, but not).
She also used a teacup, but I eyeballed the one she used, and made a pretty good stab at it. After watching her, I knew what it was supposed to look like, and I now think mine are actually better than hers.
We get by with a little help from our friends