The next thing I had to do was attach the metal to the inside of the back panel for the magnets to catch on to. This was fairly easy - I laid out corresponding holes to the magnets I installed on the back of the jukebox shell and then used my plunge router to remove some material in the back panel so the metal catches could sit flush. Then I used some two-part epoxy to glue the metal catches in place.
This is what it looked like all clamped up:
I haven't actually tested it yet to see if the panel stays in place like I'm hoping but I will tomorrow.