I started with measuring and rough cutting the bottom panel. I can usually cut things pretty close with the bandsaw which was the case with the bottom. Next using the belt sander and files I got the bottom panel to fit nicely.
Next I marked where I wanted to cut away parts of the two angles on the top of the compartment in order to give a little more hand clearance as the extra metal is unnecessary for strength of the set up and just is extra weight anyway. So I put them in the mill machine and then deburred and finished off the edges.
I drilled the location for four screws to hold the bottom in place.
Bottom cut and fit
The bottom is to keep stuff from falling through LOL