this is Ayato's mask from tokyo ghoul:re. his mask is in 2 parts in the show.
solder and paint
First either glue or solder your top pieces together. After that paint the ears red and wait for them to dry, Once dry cover the ear up with painters tape. Then paint the whole mask black.
If you want to wear the mask then glue some elastic straps on the inside of the mask so that it fits your face.