A 25-year-old man presents with acute onset right-sided pleuritic chest pain and shortness of breath. He is tall and thin, and smokes cannabis occasionally. On examination, he has reduced breath sounds and hyper-resonance to percussion on the right side. Chest X-ray confirms a large right-sided pneumothorax with 3cm rim of air. He is clinically stable (RR 22, HR 90, BP 120/80, SpO2 94%). What is the most appropriate management?