Been tossing around an idea for a nearly minimalist bookcase idea. i think it might work, but i wouldnt load it with anything too heavy on all but the bottom shelf (or the very center of the middle!). I think, also, that the corner joints of the top and middle shelves would be strongest as through dovetails. the two sets of parallel beam supports in the back would be notched/dadoed to accept the shelves, which might be good partially notched as well. one missing dimension in the figure is the width = 10”, again trying to minimize the stress on those nearly free-floating shelves.
“bookcase” might actually be a misnomer – if it’s simply meant to hold small objects, like nicknacks or pictures, and maybe a couple books, it might work a little better.
as far as species goes, I keep thinking walnut and maple, not too exotic, but nice contrast.
this also serves as my entry into sketchup design… which is useful/fun.