To expand on what I mentioned earlier, the curved side panels were made using 7 layers of 1/8" MDF laminated in a vacuum press over a curved form.
As for cutting the angles to match the curved sides, I drew the speaker in CAD and simply measured the angles where the front/rear baffle and braces intersect the sides. Since the sides are curved and not a straight line, this angle is just an approximation; however, they are only off by a few thousandths of an inch at the center of the panel edge so I don't worry about it. Since there is some springback in the panels when done in the vac press and the curvature is is off slightly from the theoretical, I fine tune the angle on the tablesaw to get it to match the top and bottom very closely. Usually the actual angle isn't off by more than a half degree vs the calculated.
Hope this helps.