The game begins with no Walls in play. Instead, the die is rolled to determine how many walls will be in play at the start of the game.
Then, the die is rolled to determine the arc in which each Wall will be placed. If a number is rolled where a Wall already exists, the die is rerolled until a new placement is determined.
As another option, players may simply choose a set number of Walls (e.g., 3) that they wish to start the game with and roll the die to determine where to place those Walls.