Complex sentence: It was designed as a more environmentally friendly alternative to the longbox which was often discarded after purchase with the being mostly paper packaging that is folded into the shape of a traditional CD case once purchased.
Split into simpler sentences: It was designed as a more environmentally friendly alternative to the longbox which was often discarded after purchase. With the eco-pack being mostly paper packaging, it is folded into the shape of a traditional CD case once purchased.