UI for enumerated OpenType font features

Can you think of a tidy and efficient way to present 1–99 different text display options to users, given that

1. more than one option may be active at any time, and
2. text selection may include multiple options applied discontinuously.

I am thinking about things like OpenType Layout Character Variant features (cv01…cv99), or if the number of registered Stylistic Set features (ss##) were increased from 20 to 99.

Originally asked on Twitter by John Hudson