All our Raeli ovens are usable by anyone. You can take all the tiles you fire. All colours have been found.
We are joining the "prepaid for the whole tale non-player" army. If you are looking for us, you will find us at Gobbler Game.
The ovens will not be further upgraded, since we don't believe the effort of upgrading them should go into breaking tiles like this:
Thanks to Aidenna for adding the map