  Controlled micro- to meso-scale porosity is a common materials design goal
with possible applications ranging from molecular gas adsorption to particle
size selective permeability or solubility. Here, we use inverse methods of
statistical mechanics to design an isotropic pair interaction that, in the
absence of an external field, assembles particles into an inhomogeneous {\em
fluid} matrix surrounding pores of prescribed size ordered in a lattice
morphology. The pore size can be tuned via modification of temperature or
particle concentration. Moreover, modulating density reveals a rich series of
microphase-separated morphologies including pore- or particle-based lattices,
pore- or particle-based columns, and bicontinuous or lamellar structures.
Sensitivity of pore assembly to the form of the designed interaction potential
is explored.
