The present specification is directed to a seal forming structure (3100) for a patient interface (3000) for delivery of air to a patient' airway, wherein the seal forming structure (3100) comprises a first section (3150) of a thermoformable material and a second section (3160) of another material. The present specification is also directed to a patient interface comprising such a seal forming structure (3100), wherein the patient interface (3000) further comprises a shell (3250). The specification is also directed to methods for manufacturing such a patient interface (3000).