Pick the spot where you want to build your course before you draw up your plans, since you might have to account for narrow spaces, low-hanging tree branches, or other environmental factors. Pick a spot that's free of dangerous obstructions like protruding tree roots or sharp rocks. The best place to build is a big, open backyard where you'll have plenty of room to run, jump, and swing. Take measurements of the space where you want to build so you can plan the exact dimensions of your course. Popular obstacles include the Salmon Ladder, Warped Wall, and Quad Steps, but with the right materials, you can replicate many of the challenges you see on the show! Choose obstacles that will work with the space you have. For instance, if you have a very narrow backyard, you might want to build only a salmon ladder. If you can't dig post holes in your yard, you might only build the quad steps. Don't be afraid to get creative! If you have a sturdy tree branch in your yard, for instance, you could hang a series of ropes from the branch to create your own Tarzan Rope, where you must travel a distance by swinging from rope to rope. If you're including several Ninja Warrior obstacles, decide how you want to go through them. The order changes sometimes on the show, but the Quad Steps is usually the first obstacle, and the Warped Wall is usually the last, but you can arrange your course however you want. Try arranging your obstacles in varying intensity. For instance, if one obstacle requires a lot of upper body strength, try following it with one that builds your balance, then one focusing on leg strength. Draw the obstacle course exactly as you picture it on a large piece of paper, using the measurements you took from your yard. By having a blueprint, you can plan out exactly how your obstacles will fit in the space you have available. Having a plan in advance can also help you design your obstacles to be as safe as possible. When you're drawing a blueprint, you want to draw to scale. For instance, you might decide that 1 inch (2.5cm) on your blueprint is equal to 1 foot (0.30m) in real life. In that case, you would draw a 12 feet (3.7m) post exactly 12 inches (30cm) tall on your blueprint. Your blueprints should show a top view and a side view to help you picture it as you build. If you're using found materials to build your course, try to gather them up before you draw your blueprint, since they could alter the dimensions of your plans.

Summary:
Find a good spot to build your course. Decide which Ninja Warrior obstacles you want to include in your course. Decide on the order of your obstacles. Draw your blueprints.