I made one for the 2004 Finals. I went a "little" extreme...it's damn near full-size. It's about 1" too tall. I could get it into the arena for a couple of reasons:
#1) It's not metal so the metal detector wands didn't declare it a weapon. It's made from a solid block of foam on a hot wire machine. Then it's sanded and painted.
#2) My season ticket seats are at the top of the section and I can stand to watch the game. I had to place it on the floor in front of me. It did make a nice place to set my beers.
Denis Potvin wasn't too thrilled when I held it up because it blocked his view in the media box and he couldn't see to call the game. He threw a media guide at me to get even.
I'd keep it simple and make sure that security at the arena doesn't have an issue with it.
Here's a pic of mine next to the real one:
