  The recent paper 1809.01197 described how states of a holographic CFT can be
approximated by states of a large collection of non-interacting BCFTs, such
that the dual of the new system accurately approximates an arbitrarily large
causal patch of the original geometry. In this paper, we first describe in more
detail the geometries dual to such discrete BCFT systems, emphasizing that they
are multi-boundary wormholes in which it is not possible to move causally
between different asymptotic regions. By reintroducing couplings between the
BCFTs in various ways, we show that the wormholes can be made traversable,
giving an intermediate class of geometries that interpolate between the
multi-boundary wormhole and the original geometry that it approximates.
