Genius idea! I have always wanted to do that. I often buy palettes and don’t end up using all of the colours in them, so this would give me a chance to choose colours that I know I will definitely use. When you visit the MAC online store, you can choose to either create your own eyeshadow palette or blush palette. You can choose the amount of eyeshadow shades you want (4, 6 or 15) as well as the finish of the eyeshadow (frost, lustre, matte, satin, veluxe pearl, velvet). Happy choosing!