By simple immersion of high-aspect-ratio macroporous silicon in a prepared nickel bath, replication is achieved in a single step via whole nickel displacement over the silicon of pore sidewalls while maintaining the original macroporous structure. The resultant nickel sidewall skeletons are nanocrystalline and nanoporous. The as-formed featured nickel films are able to self-peel from underneath the nonporous silicon base. The figure shows the Ni wall between two pores.