Here is a great little card called a tent card. I recently learned to make it ...kewl, huh? I think it is perfect for a mortarboard card but you should give it a try for some other designs as well - really nice!!!
I made the tassel myself from DMC floss - really easy to do!
I like the colors of this card - Calvert Hall colors (a local high school that my brother, father and uncle attended - and I worked there too - my first job as a teenager...five summers!).