@shplink I'm working on an English spelling reform proposal. I was tempted to use "ʌ" for the vowel in "cup". But the most graphically obvious way to capitalize it would be "Λ" - which both my Greek colleague and my own hellenophilic tendencies rebel against.
I think I'll go with "ə". Which I gather is capitalized differently depending on the language that uses it: either "Ə" or "Ǝ".