Create a high-quality, beautifully detailed cover image for an art portfolio on Mintable. The image should be rectangular and have the aesthetic of an artistic painting, rendered in 3D with a .glb format. The scene should be vibrant and visually captivating, featuring a palette of rich, harmonious colors. Incorporate elements like a paintbrush, palette, and easel, symbolizing the artistic journey. The background should have a soft, ethereal feel, with subtle hints of texture and depth, giving it a slightly surreal and dreamy appearance. Ensure the overall composition exudes creativity and inspiration, making it an enticing and attractive cover for an art portfolio.