Brenthaven has introduced its new line of cases for the Apple iPad. Featuring an external shell made from 100% recycled Billboard material, the eco-friendly Bill-Fold Sleeve for iPad also offers a folding design for added corner protection, and a white-on-black color scheme. It will ship April 3 and is available for pre-order for $35. The Ecco-prene Sleeve is also an eco-friendly case option, made with a neoprene-like material that is PVC-free and…