Yeah, the Max caps are what Fizzerific had already linked. Sadly they aren't customizable either.
Also the modifiers are slightly less useful on a Ducky Mini that's going to be used on a Mac. The bottom row is Ctrl, Alt, Cmd, Space, Cmd, Fn, Pn, Ctrl which means I'd need only one alt, but 2 of their "Win" caps and 2 Fn caps.