We spent hours playing Ocarina of Time on the good old N64 Nintendo system, and I knew that it wasn't so obscure that I would have to explain it to people all night. Also, it would be pretty easy to put together in a few days. I could find a green tunic at Goodwill, buy a cheap plastic sword, and get some foam board from Hobby Lobby to make the shield. It turned out to be a fun project. The sword was easy; all I had to do was paint some of the hilt accents blue.
I got a piece of grey foam board for the shield and cut out the general shape. The interior background is blue, so I painted it the same blue as the sword for continuity.
After that I cut out the interior shapes to add a little texture to the flatness.
After a paint job I glued the pieces down. It looked good, but it needed a little more dimension, so I cut some random geometric pieces to go around the edge in the grey part.
Turned out pretty good, I think! The last step was to add some handles on the back so I could hold it as a real shield. I picked up some brown duct tape at Hobby Lobby, planning to use it to fashion a sheath for the sword, and it turned out to work on the shield as well. I was all ready for Halloween the next night!
(photos collected from media.moddb, by e.hunt, r.hunt, and gamasutra)