Essencially, Spaghetti Diagrams are maps of the area that you are working in. The maps (floor plan) can be hand drawn, or computer generated. They consist of paper and a colored pen /marker or two.
Spaghetti Diagrams are an inexpensive tool used to track flow; the flow of people, paper, product or information. These easy to construct maps also allow you to track time, distance and value / non-value added steps in your process.
Start with a layout of the area. If layouts are not available the one step equals 3 feet & 1 second will give you a good starting point. Define the starting point of the flow you are tracking. Start lines to each of the next steps until the process is complete. The messier the better!
Spaghetti Diagrams will quickly identify time and distance traveled. The maps will allow you to instantly observe if your proposed changes will reduce non-value added motion, and by how much.
Here is an example of a spaghetti diagram I made tracking ONE mission: Buy a pair of pants from GAP. Shopper #1 is my wife, and Shopper # 2 is me...