That is from an oldie but goodie project from 2011. I couldn't find the shop drawings for the bookcase in our archives. Looking at it and knowledge from previous projects. I would say the shelves are 1.75" thick with 13" vertical spaces and random lengths. The 1.75" thickness allows you to wrap 1/2" steel tubing [connected back to the framing] with a 3/4" mitered cabinetry veneer - for the floating aesthetic. The 13" spacing allows room for vinyl albums [which is 12.375"]. Have fun with it..