If you've done the quest then I guess you should go make some cool stuff. After a certain point, the trainer will no longer be able to teach you things to make. You will have to find patterns that drop off random mobs or buy them from the AH (which could be costly).
The quest for elemental leatherworking is a little high for my 43 so I'm waiting a little while, which means I have no experience and can't really tell you what to expect.
Good luck.