Create a sleek wand component system. Use the existing sleek spots and probably double the number of them. Give mages 12 component spots - 4 different aura components, 4 different sleek components, 4 different black components at character creation. It takes 3 components to create a wand. If you use 3 of the same compoment, you get that type, if you mix and match different components , you have varying odds of getting any of the wands.