Is there an easy way to draw ascii symbols in linux?

I want to draw the boxy stuff (alt-218, etc) in the Mystic prompts editor, but I can't figure it out despite my Googling.

I read something about CTRL-SHIFT-U followed by the code, but that didn't work for me. Am I close?

--- Renegade vY2Ka2
* Origin: Joey, do you like movies about gladiators? (1:229/426)