Created in Gemini from the following prompt:

"create an html/javascript program to simulate moving balls trapped within a hexagon and bouncing off the inside sides of the hexagon and off each other when the collisions occur using realistic physics.  The user should be able to select between 1 and 20 balls through a variable or user interface component. Select random colors for the balls."

This completed with no revisions and is 440 lines of code.