Oscar the Grouch:
In order to create Oscar, I had to recruit a friend who was able to cut the bottom off of a metal trash can. He cut off the bottom, I drilled holes in each side and used a thick ribbon rope to create straps. I then coated the rough edges with duct tape to ensure that it would not cut me. For the trash can lid, I took a wide headband and used A LOT of hot glue to affix it to the middle of the lid. then just wear the headband on top of your head.
For the rest of the costume, I used green eyeshadow to color my face and give it a softer green glow, ratted up my hair, and used green tights ordered online. For the top, I just cut a hole in the crotch of the tights and wore the arms over the top of a green camisole. The bottom tights were just worn underneath a pair of green cutoff leggings.
Couture Big Bird:
Took a plain white dress and used a hot glue gun to glue feathers all over.