While looking for a method to hand-write the IPA, I got side-tracked into looking for handwriting fonts.
One of the ones I found was Pecita, which is licensed under the SIL Open Font License and even has a repository letting you install it directly into Ubuntu. It also comes with a fairly large repertory of characters, including Katakana, various mathematical symbols and arrows, IPA, and Greek.
Pity it’s so illegible, though! At least to me.