What is full of holes but still holds water?

I'm round in the beginning, high in the middle and round at the end

I hold your papers or show a scene, one keeps things tight, one plays on screen.

Green from me, they say you turn, a simple sin, from the ten. You see others, with their possessions, then it's time, to go to confession.

I am a pit of darkness that bleeds with a feather's touch. I hold the lamp black ichor of the written word inside me. Who am I?