I am putting up 3/8" plywood on top of old plywood in a carport ceiling. This will add to the thickness of the ceiling and bring the ceiling down 3/8". I would like to keep the old octagonal metal box which was nailed into a ceiling stud and which housed the ceiling light fixture. The old metal electrical box was perfectly flush before the addition of the new layer of plywood but will now be 3/8" below the ceiling surface. Can I just attach a 3/8" piece of plywood onto the stud and nail the box through the 3/8" piece of plywood into the stud, thus bringing the box flush with the ceiling? Or, is that not the right way to do this?

Purchased new ceiling fixtures with screw on decorative end caps. The end caps are not stripped, but they are too loose and wont securely tighten (ie spin freely)-almost like they are a 1/2 size "too big" I Like the fixtures so prefer not to return them. Need to be able to unscrew them for occasional cleaning so glueing them on is a bad idea. Currently I tightened them onto the bolts by adding a few tiny strands of cut copper wire from an electrical cord-similar to the trick of adding wood strands to a screw hole-- and then they sort of screwed on and seem to be holding. Does anyone have any other or better suggestions -I'm not sure if this will be secure enough long term? The 4 end caps secure a 2 pound glass bottom to the lamp...