I made her tail entirely out of tape, except for the cardboard fin. It's pretty crappy-looking at this stage, but you can see how it was constructed, more or less. It's not hard to make things out of tape (fairly sturdy things, even), but it takes a lot of patience. Duct tape seems to be popular for this kind of craft, but I think masking tape is easier to work with. You just need more layers to get the same kind of durability.