I'm another who just makes an X on a paper plate with a felt pen.
For up close, I use a sharpie, and make a fine X (rimfire at 30 yards)
If shooting farther that 100 yards, just use a bigger felt pen.
I've got one that's 1/2" wide. Works great for distance, and handguns.
Been doing this for over 20 years.
Virgil B.