That wouldn't be a one-time pad. It would be a substitution cipher. Substitution ciphers are extremely simple to break. I don't think there is any way to imple

That wouldn't be a one-time pad. It would be a substitution cipher. Substitution ciphers are extremely simple to break. I don't think there is any way to implement an actual OTP with a font, but you could use the font as a code book, where each character in the cipher text goes to a random unique code point, with the font duplicating each character many times.