I acquired a nice thick clear plastic cover a few weeks ago.
It came back along with my Passport and Brazil Visa
from an agency in Houston.
However, I am still using the Ostrich skin cover
that SQ gave out years ago !
It doesn't always work as intended, though....
checking in for AUS-CUN on AA recently,
the agent checking docs asked me
to take the passport out of the cover.
Then she stuck my baggage claim check
on the back of the passport !!
It is now VERY sticky.