Keep in mind, there are no perfect boards, but try to always use the straighter boards and avoid warping boards. Also, Brandon and I have found that when it comes to picking out lumber at Home Depot and Lowes, they tend to stock up on fresh boards a few days before the weekend starts (so Thursday/Friday). And then, on Sundays and Mondays, the boards are usually really picked over and there isn’t a good selection. Just another tip to keep in mind!
Cut off a 21-in.-long board for the shelves, rip it in the middle to make two shelves, and cut 45-degree bevels on the two long front edges with a router or table saw. Bevel the ends of the other board, cut dadoes, which are grooves cut into the wood with a router or a table saw with a dado blade, cross- wise (cut a dado on scrap and test-fit the shelves first!) and cut it into four narrower boards, two at 1-3/8 in. wide and two at 4 in.
As soon as I came across this tutorial, I didn’t wait any longer to start building one. Some of the items you need for this project are hardwood plywood, saw, glue, nails, drilling machine, etc. The video is very easy to follow for anyone with basic woodworking knowledge and experience. The first source link also includes a step by step procedure in plain English for those, who are not comfortable enough with the video tutorial.