Looking at the zompist page for Wede:i, I don't see any instructions on how to pronounce the ":" that we see in the name of the language and other places.
Am I missing something? How are you supposed to pronounce the ":"?
The phonology table shows it quite simply, it modifies the
e to indicate that it is a long vowel. I don't know why the vowel table shows the dipthongs
a:u but not
e:i (or any others).
Note that although this may seem to be a common colon, the actual IPA diacritic is two triangles, flat sides on the outside: U+02D0
ː. But as the colon doesn't have another meaning in the IPA and it's much easier to type, a lot of people just use it instead.