This animation was created by Dietmar Strube. His process:
1. Draw and save 50 BMPs using Winplot.
2. Open IrfanView. Batch-convert the BMPs into GIFs, resizing them to 200x200 pixels.
3. Open either unFREEz or Animake. Drag the 50 individual GIFs and save as a single, animated GIF.
Three more of his examples: