I am new to this website and was wondering if I could get any ideas on making a graduation cap on a cake. I was going to make the mortar board out of gumpaste. Is that a good way to go or do you think I should use something else. Thanks!

radtech,
Welcome to CC.
I have made 2 grad caps and for both I baked a VERY thin square cake for the mortar board. I think the result looks nice and it's a little extra cake for the client (about 4 servings).
You can see them here:

http://cakecreationsbyjulia.com/images/cakes/Grad01.JPG

http://cakecreationsbyjulia.com/images/cakes/Grad02.JPG

I covered a piece of foam board with fondant for the top of the hat. I wanted something light that wouldn't tip too easily.