Nullcell-F3 is a closed-cell CNT aerogel foam developed by Tessera Materials, produced by freeze-casting a CNT suspension into a hierarchical porous structure and then critically point-drying to preserve the three-dimensional scaffold. The resulting material is 99.2% void by volume — lighter than almost any competing solid — while the CNT cell walls provide exceptional structural integrity under compression and outstanding thermal insulation across a range from cryogenic to 1,400°C. Its acoustic damping properties are a secondary benefit that has driven significant adoption in architectural and vehicle applications.