This gave me an idea for a gimmick die. Transparent die filled with dark liquid. The exterior of the die has the usual numbers in white lettering. Inside the die, there is a smaller cork die that rises like a magic 8ball. It’s 2d(x) in 1. Interesting for tension building, if nothing else.

Edit: looked it up and I’m not original, and they’re largely as bad as I thought they’d be