In the past we do the mural layout by using cutouts of the images submitted by each and every mural workshop participants. We then compose a puzzle until we arrive at a satisfactory overall design and layout, after which a final layout is drawn or painted by hand on a piece of board. The size of the board is proportional to the actual size of the desired wall.
Now by using Photoshop things are a lot easier as the computer could facilitate the design process. Yet there is one concern - people might gradually or completely forget the importance of hand drawing and sketching.
In this stage we now have several elements added on the design as they play important roles in the unfolding of a collective product of several imaginations.