Blue Kazoo has really made some impressive enhancements since launching the Sustainable series. I was somewhat lukewarm on the original Classic series, due to the gloss/glare and the mediocre grey card stock. The new line has glare-free pieces, and beautiful blackboard stock which is beautiful, dense and supreme quality. The pieces seem a bit less tight-fitting than the Classic series, but tightness of fit is not of much importance to me. I do think their piece shapes are among the easiest o...