In terms of materials, everything needs to be durable, weatherproof, heat resistant, and easy to clean. This means rot resistant wood (such as teak, redwood, or cedar), stone, and stainless steel. Also, think about how hot materials get in direct sunlight, or even just warmer temperatures. Since you'll most likely be using this during the summer, you don't want to build your backyard kitchen out of something you'll barely be able to touch!
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