I am going to make a graduation cake in a few days and it is going to look similar to the top two tiers of this cake:

My question is about the tassel; do I make it and let it dry in the shape I want before putting it on the cake or do I make it right before I put it on the cake? I am concerned about it breaking from its own weight..will I need to use a wire? 

I make these all the time. I use my extruder and gumpaste, and give the end a little pinch to hold it together.  Then I place on the cap while its still soft. It will then harden and be just fine.

Ok, thanks lorillc. So the strings don't stretch or break from their own weight while they are still soft and hanging there?

No, they haven't yet. If your still a little worried about it, let the tassel sit for a few minutes (just to toughen up) before placing on the cake.  :)

I made one last week and it made a 5 hour trip and I was a little worried about that one, but the lady said not one strand broke.

Ok, thanks for all your help!