Complex sentence: After everything is mixed the pyrotechnician proceeds pouring 10 grams into the tube, a 3.4 "paper disc is now punctured with a 3/32" fuse hole.
Split into simpler sentences: After everything is mixed the pyrotechnician proceeds pouring 10 grams into the tube. Next, a 3.4 "paper disc is punctured with a 3/32" fuse hole.