ABSTRACT. We aim to showcase the wide applicability and power of the big pieces and suppression methods in the theory of local T b theorems. The setting is new: we consider conical square functions with cones x ∈ R n \ E : |x − y| < 2 dist(x, E) , y ∈ E, defined on general closed subsets E ⊂ R n supporting a non-homogeneous measure µ. We obtain boundedness criteria in this generality in terms of weak type testing of measures on regular balls B ⊂ E, which are doubling and of small boundary. Due to the general set E we use metric space methods. Therefore, we also demonstrate the recent techniques from the metric space point of view, and show that they yield the most general known local T b theorems even with assumptions formulated using balls rather than the abstract dyadic metric cubes.