Molding Tag Box in to a civic bumper.

Does anyone know how you mold the tag box in to the bumper? I am mostly just wondering how you get it to stay attached to the bumper cover since you cant weld it.
 
Any help appreciated.

Fiberglass

if you have a stock bumper fiberglas wont stick really well. i would use abs epoxy. you can get it at a hardware store..

I would use fuzor extreme bumper repair adhesive, you will have to get other plastic(would be best to use another piece of the same kind of plastic) to make the tag box itself then glue it in. Fuzor also makes a topcoat like a body filler made for plastic. just make sure u give it ample time to dry in sun because it will shrink a lil

fuzor  no glass wont stick