Deku Cosplay: How does one make the Mask and Shoes? (Gamma Costume)

So I'll be cosplaying Deku (Gamma Costume) this Halloween. I've decided to start work on the costume early, so I don't end up rushing in the last week and messing it up. I've planned everything, and know how to make most things, except for the shoes (black/dark grey cover things) and the mask. I was thinking of 3D printing the mask, only issue is, I can't find a model for it anywhere, and I don't know how to make one myself. (Just to clarify, this is the mouthguard I'm talking about, the hood with the ears should be fine.) If anyone has a model of the mask, could they send it to me please? Or, and this is a lot to ask, but if anyone could make me a model of the mask, it would be very appreciated.

And one more thing: As I'm an anime only watcher (though I've seen pictures of the Gamma Costume) Deku is yet to put his hood on in his new costume. Does the hood go over the mouthguard or under it? I would've thought it goes under, but I've seen fanart where it's hanging on top of it.