<I used 5/8" plywood and 2x4 all around mounted vertically for extra <support for the shelves. I would not use anything less. Try sticking a <couple S-100 chassis on a shelf of 1/2" plywood or supported with less Err... I've done it and 1x2 and 1/2" play do it real well and I do have a few s100 crates. <than a 2x4 and unless you have additional support in the way of diagonal <cross-members or extra support underneath the shelf it'll bow or break. <Maybe not right away, but with time it'll start to sag. the trick is you box the underside of the shelf in 1x2 and put one down the middle for support. then that assembley is screwed to a 2x4 at the corner and a pair of diagonal braces on the back of 1x2 and side if needed. Use wallboard screws to assemble rather than nails, they hold better. <It saves much time to use steel brackets instead of cutting slots into the <wood. I did my first shelf with the latter design and it took a long What slots? It can be sone that way but it's not a required thing. <If I had to do it over I'd buy pre-fab shelves like the Gorilla racks. They are nice and all but the wood can be cheaper especially if you can scrounge. Also wood can be configured for odd sizes like a 27" wide space between the h960 and the window. ;) Allison