May I give my 2 cents here?
If you can copy the foam part and the problem are just the small plastic "loops" used to mount them to the mouth piece, you could still do it and:
1- Use loose zip ties to hold the throat protector to the mouth piece; or
2- Use a different way to do it, like maybe a small bolt or something like the parts used to hold the soft ears to the JT frames
As you are re-inventing them, you can tweak the design in any way it's more feasible to you.