I made my own amplifier cabinet based on Dave Hunters measurements. He suggested 20 inches long, 16 inches high and 10 inches deep. Based on your woodworking skills it is not too difficult. I mitered the corners and I used wood bisqits to secure corners with wood glue. I used popular a semi hardwood which had to be glued together on edge to get the 10 inch width.
Then the baffle board I used 1/2 inch baltic birch. I went on You Tube and typed in Dave hunter 2 stroke amp and looked at the video that showed the cabinet from weber speakers which was part of video on assembling the 2 stroke.
I would suggest building the cabinet 1 to 2 inches wider and higher. I made mine 20 by 16 inches, but it was a tight fit. it worked out fine but if I build a similar cabinet I would probably make it bigger. Cutting the notch for the chassis is a bit tricky just cut a templet first before making the final cuts on the real cabinet. lots of luck. Also I used the 8 and 10 ich speakers if you one 12 inch it would not be so cramped.