Brass and copper effect Steampunk mask 

I used a hot melt glue gun to hold it in place. And then a second application from the glue gun to make a stronger bond over the top of the mesh on the inside. If that dosn't work try sanding the mask on the inside to form a rougher surface for the glue to bind to.

eBay just look up airsoft masks.

These masks you can buy off Ebay. Search for Airsoft masks. I'm not sure what you mean by mopped up.

I mean some colours that doesn't disappear for a long time...

Best way to protect the paint is to spray clear varnish over the top. Either gloss or matt varnish depending on how you want it to look.