The shelf in the first picture is made of red oak plywood. You can choose the wood type, color and design as you like for your project. In case if you need more help understanding this project, you can refer the source link below. It discusses various items used, steps and tips and personal experience of the author who personally built a Zigzag shelf.
It might not be the easiest project in this list, but if you already have some experience with wood cutting and joinery, it won’t be any hassle at all. Thanks to the extremely detailed instructions it shouldn’t really be a problem even if you’re not very familiar with woodworking. This could actually be a great project for refining your woodworking skills as a beginner!
Pocket screw joinery is a system—employing special drill and driver bits—used to join boards or pieces of plywood to one another. Installing pocket screws involves using a jig to drill a sharply angled, 15-degree hole through the back of one board, then driving a special screw through that hole into the second board to draw them tightly together. Learn how to use pocket screws here. It’s often used in cabinetmaking and furniture building. Here’s how to build cabinets with pocket screws. The term “pocket” comes from the design of the hole which contains an upper “pocket” for the head of the screw to push against; this pocket also hides the head of the screw.