The solution called for building two 'end units' that would serve both as mini-book shelves, and more importantly, as the end supports for the glass shelves. I ended up going with 3/8 tempered glass, 8" deep by 48" length (approx 46.5" span), and, with 12 pieces per shelf, I see hardly any deflection. To say the least, I am *extremely* pleased and happy. My first display system and it is great.