What I have now is just a bolt through the front and tnut in the
rear. I managed to get the rear one inserted and placed with
a bar clamp. I drew down the nut by tightening the clamp because the
carcass was together already. The build sounds pretty good-- I tested it with my ears last night. But for permanent placement I need grilles.I think I'm going to try that system that Bill Fitzmaurice talked
about using pet screen and snap together parts for making a screen door.
Those stiles and rails can be cut to length and width, come in several colors and the pet screen is stretched over the frame. All this stuff
is available at the Home Depot. If I have to surface mount the magnets
I'll just have to experiment.