Create a detailed illustration of a building block with a rectangular shape, smooth texture, and a vibrant color palette, featuring a mixture of primary colors such as red, blue, and yellow, with a subtle gradient effect to give it a sense of depth and dimension, placed against a neutral background to highlight its shape and color, with a slight shadow at the bottom to imply a sense of weight and presence, and a few subtle highlights on the surface to suggest a sense of reflectivity and materiality.