Thanks for pointing me in the right direction. I don't really know my glues.
As far as visible lumps/marks on the fabric, though, I would be sticking this to the back part of the mask, so I don't see that being too much of an issue. That and I think I'd be using pretty thick cloth. Mostly I'm concerned with durability. If there isn't much difference in that regard, I'll probably try the tacky glue or fabric glue when I do that, since I might have one or both of those already.
Do you have a dream costume you'd like to make?
Group cosplay space pirates of multiple generations. Carrying a boom box loaded with space pirate music.
Another, more doable one would be a squad of Dai Li agents from Avatar: The Last Airbender.