That finish looks outstanding, well done!
For the copper tape to work as a Faraday Cage it needs to be earthed (that is connected somehow to the earth wire), you might want to lip the copper tape out of the holes so that it contacts the control plate (which is earthed through the pots) and the underside of the bridge so the whole box holding the electronics or pickups is earthed. You could run a strip from the front pickup to the control cavity under the plate.
http://whatis.techtarget.com/definition/Faraday-cage