Pliobond is a contact cement, over here there are several made under different names so I'd guess you have an equivalent.
It's applied to both pieces to be glued. allowed to tack up & put together. You have to be sure of the placement before they're allowed to come together because they aren't coming apart.
I went hunting locally, and found some matte black card from an artists supply place, which I've used, with flat black enamel paint on the areas under the mirror pivot arm where it was impractical to put the card. It looks really good now.