She later became interested Paul Wegener a German actor, writer and Director. As a young women, Reigniger managed to find a job in designing inter-titles for his films. When working on the film The Pied Piper of Hamelin (1918), Paul Wegener had a problem when it came to animating live rats! They even tried guinea-pigs. So he asked for Lotte's assistance!
"So it had to be wooden rats and stop-motion. We were again hidden in our cellars, loaded with wooden rats this time. The Piper piped, the shot was fired and we put our rats out of the window and withdrew hastily. We came out again, moved our rats a fraction, withdrew again, and doing this from five o’clock in the morning until the sun was setting we really had moved our rats all along the street."
Lotte then discovered the experimental animation studio, called the Berliner Institut für Kulturforschung, where she worked along side Bertolt Brecht and her future husband Carl Koch. This is where she practiced and refined aher artistic approach to film making!
Here is one of her animations for you to enjoy!