Some progress on the rear panel. First time working on metal. far from perfect... but it should do the job and I can hide most crimes with edge trim.
Started out using a jigsaw, but even with using a straight edge clamped to the work, the blade would walk all over the place. I chalk it up to a crappy jigsaw (cordless black and decker). Then I switched to left, right, and straight aviation snips. Sometimes hand tools are the best. For the cutout I used a hand nibbler.

Next step is to add rivets to secure the panel at the top with knobs
And I will add aluminum angle to the top, bottom, and side for some strength, as after I cut out the hole it was very flimsy.
Started out using a jigsaw, but even with using a straight edge clamped to the work, the blade would walk all over the place. I chalk it up to a crappy jigsaw (cordless black and decker). Then I switched to left, right, and straight aviation snips. Sometimes hand tools are the best. For the cutout I used a hand nibbler.

Next step is to add rivets to secure the panel at the top with knobs
And I will add aluminum angle to the top, bottom, and side for some strength, as after I cut out the hole it was very flimsy.