Heat transfer from a surface depends on the surface area of the surface exposed to convection. Porous structures are one that has high surface area to volume ratio. For a given porosity the surface area can be maximized by varying the fiber width. In the present study a unit cell model like a Rubik's cube is considered. The cubes formed by changing number of single cubes in a raw are also considered. The fiber width corresponding to maximum surface area is found for porosity 0.45.