Adding A Zipper Or Velcro To Mask

[🪦 Dagon ●]

I\'ve never done this before, but from the pictures of masks I have seen it looks like a very nice little feature to add. Especially since most masks that I do have always "pop up" with nothing to hold the slit down. So I was wondering how to go about adding something like this- as far as the best materials to use and maybe a walkthrough on how to actually do it. Thanks.