Hand lay-up is a manual process used in composite manufacturing, where layers of resin and reinforcement materials, such as fiberglass or carbon fiber, are applied by hand. Workers lay down sheets of the reinforcement material in a mold and then saturate them with resin, ensuring even coverage. This technique is often used for creating large parts, like boat hulls or automotive components. The hand lay-up method is valued for its simplicity and low cost, making it accessible for small-scale production and custom projects. However, it can be labor-intensive and may result in variations in quality compared to automated processes.