  In this note we present some abstract ideas how one can construct spaces from
building blocks according to a graph. The coupling is expressed via boundary
pairs, and can be applied to very different spaces such as discrete graphs,
quantum graphs or graph-like manifolds. We show a spectral analysis of
graph-like spaces, and consider as a special case vector-valued quantum graphs.
Moreover, we provide a prototype of a convergence theorem for shrinking
graph-like spaces with Dirichlet boundary conditions. (Dedicated to Pavel
Exner's 70th birthday)
