Many manufacturers have programs that let you customize the way your case looks, but what about creating a case from the ground up? The Mod Tablet 2 (all iPad minis and iPad Air models; $300 to $400) sports a completely customizable interior that can hold a wide assortment of specialized modular inserts (read: pouches, pockets, and holsters).
Each case includes a slot for your iPad, a Primary insert for storing your most important documents (like earbuds, your Lightning cable, and other objects), and a generous pocket inside the back cover. If you want to store more, you can add additional compartments inside the front cover for your iPhone, keys, and stylus, and much more. As for colors, pick between bone, toffee, cognac, cobalt blue, or charcoal.