I used 3/4" oak plywood with the corners mitered 45 degrees using a circular saw. When the sides were finished I taped them together, glued the joints, and folded them into a big open ended box. The construction went better than I expected, but the places where the glue had squeezed out and was wiped it off during assembly wouldn't take the stain when I went to finish them. Even after much sanding I couldn't get completely rid of the residual glue. The best tip that I came across was to soak a small piece of 100 grit sandpaper in stain and sand over those spots. This worked pretty well in some areas and not at all in others. The worst spots are on the back of the speakers and on the sides that face the entertainment center, so you really don't notice it too much until you take a closer look, but I sure know about it. Next time I'll work to bring the grain out more and match the finish of the entertainment center better, and stain before gluing, I'm open for any other tips!