Steel/iron is a reusable and practically unlimited resource that does not pollute when disposed of. The production of steel in itself is not sustainable, as large amounts of CO2 are produced from fossil materials in the process. On the other hand, steel products have an extremely long lifespan and offer the possibility of endless repeated reuse, which means that the vast majority of steel on the market consists predominantly of recycled steel. Bamboo is an extremely sustainable biodegradable material, with extremely fast regeneration when harvested. Bamboo, like other natural products, functions as a CO2 depot throughout the products lifetime. Cork is an extremely climate-friendly, biodegradable and compostable natural material that originates from cork oak. Cork is a rapidly regenerating resource that can be harvested every year from the same tree.