  We use the technique of deconstruction to lift dualities from 2+1 to 3+1
dimensions. In this work we demonstrate the basic idea by deriving S-duality of
maximally supersymmetric electromagnetism in 3+1 dimensions from mirror
symmetry in 2+1. We also study the deconstruction of a non-supersymmetric
duality in 3+1 dimensions using Abelian bosonization in 2+1 dimensions.
