Wulff clusters inR 2

We give the first existence and regularity results on the cheapest way to enclose and separate planar regions of prescribed areas, where cost is given by a general norm ϕ, thus generalizing the Wulff shape for enclosing a single region. As an example, we classify the cheapest way to enclose and separate two planar regions of prescribed areas for the ℓ¹ norm (“Manhattan metric”) into three distinct types, according to the relative size of the prescribed areas.