The "Extender" as posted by GoofyIsAsGoofyDies on DISboards "is anything that you care to hang on the fish. Literally anything will qualify, but in general, they are usually some type pocket organizer similar to a shoe caddy or mail organizer. They can be as simple as a canvass bag or as complex as your imagination cares to stretch."
Here is one of many made by very creative and dedicated people who cruise Disney. I found this particular one made by LuvTheEars on DISboards (where else??!?!?!). Cruisers then use the fish extender as a medium for gift-exchange. The intricacies, rules and etiquette are described at length in the forums. For the moment, the purpose of mine will be for gifts for the children "from" Mickey.
I have thought long and hard about how to make mine. I am not particularly creative nor am I a genius with a needle and thread. Having dragged my mother-in-law (She is a sewing guru. She made a life-size Gremlin costume for Malcolm) with two children to the mega spotlight at Auburn last week, it is clear that my skills are definitely lacking. As multi-talented as I like to think I am, I am dubious about my capability to be able to sew so many bits of material together. There is also the small problem of not owning a needle and thread, let alone a sewing machine. So its off to IKEA we go to browse for suitable "components" that I can hot glue together.