There are some alternate vowel characters in the Buffalo Joe™ family. You can find versions of the following letters in their respective dieresis and circumflex character slots: A, a, E, e, I, i, O, o, U, u, N, n
To use them, simply set the accented characters and then mask out the accents above the characters if you want to use them in unaccented text.
FULL CHARACTER SET
Each font in the Buffalo Joe™ family has a full character set of 232+ letterforms, including fractions, with all characters designed in the style of the font.