A box. Outer shell is 5.6 mm clear acryllic and the shelves are 4.5 mm. A little taller than prototype 1 for more buffer room and much longer.
Shelves are no longer like steps. They have been straitened out so if you look directly from above, the shelves line up perfectly, except for the teeth. (shelves should also be clear but ponoko was currently out of that size in clear)
glued with Tap Acrylic Cement