Here's the information I have posted on the FE sign up page with some helpful information and links:
June 29, 2013 Disney Fantasy Fish Extender List - PATRIOTS OF THE CARIBBEAN! Thanks for signing up for the Fish Extender exchange on the Disney Fantasy Eastern sailing. The cut off date for signing up will be April 14 (this is when cruises must be paid in full and it gives enough time for those personalizing their gifts.) If we wind up having a huge amount of cabins sign up, we may consider splitting into separate groups. If you have any questions or need to make changes after you complete the form, please feel free to PM me (Ranidayz) or e-mail me at
ranidayz@gmail.com.
Please remember that this is supposed to be fun!

You don't have to spend a ton of money or even make something by hand. Just a small little trinket to brighten someone's day. Just remember that if you sign up on the list, you should plan to give something as well as receive. You can find some great and inexpensive ideas in this thread on the Disboards:
http://www.disboards.com/showthread.php?t=1980639
https://www.facebook.com/groups/167311023398247/
Here is a link to a thread with sewing instructions:
http://www.disboards.com/showthread.php?t=1690450
If you have never done a Fish Extender before, please know that they really add to the special magic of a
Disney Cruise. The only rule is that every cabin who is signed up must exchange something with every other cabin that is signed up. There are no special dates you have to deliver, no amount you need to spend. Some people will choose to do one gift per cabin, some will do gifts for individuals, some will do gifts for both. That's totally your choice. Just enjoy!