I designed this for my mother who uses it to make what is in my opinion the most comfortable facemask. Use one of those pizza slicer-type knives to cut around it. You can use the slits to cut the smaller parts of the facemask that are shown around the 2:00 mark in the video.

Here is the link to the video:
https://youtu.be/fNAVSiQ6kKQ