Natural and reusable coffee-to-go cup. The outside of the cup is made from cork, which is both biodegradable and renewable. The inside of the cup is made from a compostable material called polylactide (PLA). The two are fused together using a patented technique (which does not involve the use of glue) to create a double wall that keeps your drink warm. Capacity 350 ml. PLA Polylactide, or Polylactic Acid (PLA) is a thermoplastic aliphatic polyester derived from renewable resources. This means that PLA is a biodegradable material made from corn starch produced by plants - natural and renewable. Lactic acid is produced by the fermentation of that corn starch, creating the fibres used to make PLA.