I made a hat with a mask out of a t shirt.
what i did first was i took a t - shirt and i cut the sleeve off the t-shirt. make sure you leave a drape for the mask part.
in this step i sewed the top of the sleeve
then you put the stitch on the inside of the sleeve
and then you take sewing chalk to mark were your eyes are and your mouth and cut out were you marked it.
and if you want to you can sew some eyebrows on the mask to add effect