At first, the shelves I made were screwed to the uprights. But once I got some tools, and a place to do some woodworking, I routed groves for the shelves. What that does is keep the shelves flat and level, and takes all the vertical strain from weight on the shelves. When you buy a bookcase, 95% of them have a piece of heavy cardboard for the back, which keeps stuff from falling through, and also keeps the unit from rocking sideways. I use 1/8" plywood, that I've heard called "doorskin". Also. store bought shelves are uniform height, but I made them with various heights, depending on what I thought I would put on them. I make the groves shallower than I should, which makes the unit harder to put together, but I like the look. The first one I ever made was redwood, but now I use pine, which is cheaper, and I like the look. But the reality is that the finish is what makes it look good. I use clear polyurethane so I can see the wood, and Elaine did most of that. [If it's polyurethane, do you call it painting? Or polyurethaning?] The last picture is different. When we moved to Moraga, Beverly's room had 2 closets. One was pretty normal, but the other was 6'x6' with no clothes rack or anything. So I made shelves. I went to the store and found that there were plastic boxes that measured about 16"x30" and came 6" high or 9" high, or 15" high. So the shelves were designed to accommodate the various heights. (The widths and depths were all the same.) What I did was make 3 'ladder' like things, one for each end, and one for the middle. Then I got some 1x10 boards, and cut notches for the ladder uprights. I put the boards through the ladders such that the boards held the end ones against opposite walls, and the notches kept the middle one in place. There's no attachment at all, it's free standing, supported by the walls. I think that Beverly slept on one of the shelves one night -- just 'cause it was cool.