ʻO ka huʻa metala he hale paʻa i loko o kahi metala paʻa (ʻo ka alumini pinepine) me nā pores piha piha i ke kinoea me kahi hapa nui o ka leo. Hiki ke hoʻopaʻa ʻia nā pores (closed-cell foam) a i ʻole i hoʻopili ʻia (open-cell foam). He porosity kiʻekiʻe ka hiʻohiʻona wehewehe o nā huʻa metala: maʻamau, ʻo 5-25% wale nō o ka leo ka metala kumu, e hana ana i kēia mau mea ultralight. ʻO ka ikaika o ka mea ma muli o ke kānāwai huinahāhāhā.

Hoʻopaʻa mau ʻia nā ʻano kino kino o kā lākou mea kumu. ʻO ka pahu i hana ʻia mai ka metala hiki ʻole ke puhi ʻia a hiki ke hana hou ʻia ma ke ʻano he kumu. Ua like kona coefficient o ka hoonui wela a e emi ana paha ka conductivity thermal.

ʻOiai ʻo ka nui o nā patent e wehewehe i nā ʻano topological hiki ke kūpono, nā mea constitutive, a me nā ʻano hana, ʻaʻole hiki ke manaʻo ʻia nā pahu metala he waiwai a he liʻiliʻi nā mea kūʻai aku i loaʻa i ka honua holoʻokoʻa.