In 1939, Pontiac Built a Transparent Car from Plexiglas
From the site:
For the 1939-1949 World’s Fair in New York, Pontiac had a special surprise in store.
Working in collaboration with chemical company Rohm & Haas, who had just developed a new product called “Plexiglas”, they created an entire body shell for a 1939 Pontiac Deluxe Six.