I started by drilling the holes in the side pieces that will hold the screws to attach the boxes to the back of the pews. Since I don't yet own a drill press I came up with a jig that would allow me to drill the angled holes. Below is a picture of the jig which was pretty simple to come up with. If I remember correctly I drilled the holes at a 30 degree angle.
The bottom panels were next. I simply ripped them at a 12 degree angle on the table saw, cut them to length on the miter saw, and then drilled pocket holes for 1 1/4 inch screws. I have a Kreg pocket hole jig that I bought on Amazon that really came in handy here.
The oak face panels were last and I kept the same setup as I did for the bottom panels on the table saw. After the panels were ripped and beveled they were cut to length on the miter saw.
Once I had finished cutting all of the pieces I sanded them with 150 grit sand paper and made preparations for the assembly.