Basic tools any builder needs..a chalk line for marking to avoid missing supports..mark both ends, put the line hook on one end, stretch the line to the other end and pop the line. You now have a mark to work from. If your supports are fairly straight, you basically cannot miss. A good hammer, tape measure, a small square, try square or speed square for marking square lines for cutting or plumb attachment of the next piece. A level is optional for plumb walls, a decent circular saw or a good, sharp handsaw(for you younger folks that really want to rough it), screwdrivers or a cordless impact driver, a drill. A good adjustable wrench or as in my case, limitless hand wrenches and/or socket wrenches in case you are wanting to use nuts and bolts.
Drawings are nice, but not necessary. Sketch what you want, add dimensions to suit, then build your idea. Plywood is limited by span requirements for houses and building codes. Chicken coops have no codes, but to minimize bowing, 24 inch centers for studs or joists for attachment. Same goes for OSB. Building supply translucent sheeting has a 24 inch maximum spacing of support, commercial translucent panels, from 2 to 7 feet, depending on profile and thickness. 26 Gage commercial steel panels will span from 2 to 5 feet. We are not building to any code, but do not want our coops to fall apart, either