Theoretically, only 450 grams of aerographene, an airy finely-structured tubular material based on graphene, is needed to lift an elephant

https://www.uni-kiel.de/en/details/news/248-aerographen

"first presented in 2012... they were the lightest class of materials in the world to date, with a density of just 0.2 milligrams per cubic centimeter... discovered further properties that enable innovations in pneumatics, robotics or air filter technology... can be electrically heated extremely quickly with up to several hundred degrees per millisecond due to their low density... able to use aerographene to start small controllable and repeatable explosions that do not require a chemical reaction"

Related: Graphene could replace rare metal used in mobile phone screenshttps://web.archive.org/web/20211220222247/https://www.popularmechanics.com/space/rockets/a38569598/elon-musk-carbon-dioxide-rocket-fuel/