Step 4: Modify mask
Once your mask is finished, wait another 10-15 minutes before removing it. If you're having trouble, try scrunching up your face, saying the vowels, blinking rapidly, raising your eyebrows, etc. Anything to stretch your skin and get the plaster off. If you haven't rubbed your hairy bits with enough vasaline, this step might be a little traumatic.
Once the mask is off your face, you can now shape it with the remaining plaster. I added more depth to the forehead, nose, and cheeks. I also added a 'ring' around the eye sockets as seen in some of the official death eater art. Once you're happy with the mask, let it dry overnight resting on a ball of aluminum in case it starts to buckle.