The size and shape of the metal powder has a direct impact on the stability of the precursor as well as the resulting foam. For this purpose, powders that increase packing efficiency are most advantageous. The use of spherical particles may result in less contact of particles which consequently leads to larger secondary pores and a higher probability of pore collapse prior to complete sintering. This factor can be limited through different compaction techniques that decrease the degree of interstitial sites around the titanium particles. However, this method also has limitations; for example, the powders cannot be compacted to such a degree that would promote deformation of the spacer (unless anisotropic pore shape is desired).