I'm following along with Kreyszig's intro to functional analysis text, where he uses $X$ to indicate an abstract set, and often uses $x$ to indicate an element of $X$. I want to match his notation, but in a way that--when handwritten--makes a clear distinction between the upper and lower case letters. My normal lowercase $x$ is more curvy, but I feel like that's not enough, and adding serifs by hand for the big $X$ is too cumbersome. I did see a professor that just swiped a line across the top of an x-shape to indicate the big $X$ but that looked sloppy to me. Maybe I'm just being too anal about it, but I like my math writing to look good. Any suggestions?
I threw the
functional-analysis tag on here because this is the context in which my question seems most relevant.
Edit: Consider that the cartesian product symbol $\times$ causes some interference as well.