  Motivated by the question of how to pattern a surface in order to best speed
nucleation from solution, we build on the work of Page and Sear [Phys. Rev.
Lett. 97, 65701 (2006)] and calculate rates and free energy profiles for
nucleation in the 3d Ising model in the presence of cuboidal pores. Pores of
well-chosen aspect ratio can dramatically speed nucleation relative to a planar
surface made of the same material, while badly-chosen pores provide no such
enhancement. For a given pore, the maximum nucleation rate is achieved when one
of its two horizontal dimensions attains a critical length, largely
irrespective of the other dimension (provided that the latter is large enough).
This observation implies that patterning a surface in a raster-like fashion is
a better strategy for speeding nucleation than e.g. scoring long grooves in it.
