We first had to make a home depot run to pick up some 1x2 boards to attach to the insides of the cabinet as nailers for plywood and 2x4s.
Here are all the pieces cut to the right sizes:
Marked off where all we would need to attach 2x4s and plywood...
This is a nifty little edge guide we made so that we didn't have to measure where to put each board. It makes them all the same and with about a 7/16th inset from the edges of the cabinet.
Inside of the left side of the cabinet, with all support pieces glued and screwed...
And the right side...
We put them together to see how well they match up. They match pretty well...
Symmetry...
It shouldn't be too long now until we are ready to stand this thing up. It will really start looking like an arcade machine then!