Instead of using felt, I used outdated or damaged clothing I had on hand. The "teeth" are made from an old pair of white polyester shorts s, the "iris" of the eye from a silk dress and the "pupil" was off of a pair of parachute pants.

I also changed the eye to look more reptilian and placed farther apart so I could make it look like a "normal" hoodie with the hood down and I could tuck the "teeth" inside.

I sewed mine and from cut to finish took a little under half hour, but it could be possible to make using a craft glue that works on fabrics and it might take even less time.