Composite structures and methods of forming composite structures are provided. The composite structures can include one or more composite structure components. Each composite structure component is formed from a composite panel that includes one or more sheets of material. The sheets of material include a thermoplastic material and a plurality of reinforcing fibers. A composite panel can be formed in three dimensions to form a composite structure component. Multiple composite structure components can be fused to one another to form a composite structure. In addition, each composite structure component and the composite structure formed therefrom can include an aperture. An interior volume can be formed between adjacent composite structure components. Methods for forming a composite structure can include a step of simultaneously molding and fusing composite structure components.