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.
An excellent introduction to woodworking is to use crates as your main material. The boxes are already formed, which means less assembly work for you—yet it looks impressive once your project is altogether. With this crate coffee table, you still get to practice your skills adding the casters and the center box. Finish with a little stain, and this table is ready to roll. You can find the full tutorial at DIY Vintage Chic.
I love a good shop tour, but it’s super motivating to me to hear you say that you built it all in a few years on good old-fashioned hard work. About 8 years ago, I lost an office job and began working with my hands, first doing siding and windows, and now installing home media systems. It has completely changed my work ethic, and my motto now is, “If you ain’t sweating, you ain’t working.”
You can also use Google image search to research a project. Unlike the PDF search, the image search provides a photo of what the project will look like, which is helpful in determining if you want to pursue building it. By doing an image search for how to build a step stool, you will have a ton of options that all lead to woodworking plans of various quality. (The how to part of these is important—otherwise you’ll just get pictures of step stools.)