One day when I was coming up with a lesson idea for showing students what folds look when the have been eroded, I kept thinking cinnamon rolls would be awesome to show them. But they might not work right, you can't really change the folds, and it would be expensive. That's when I thought of Play-doh. Basically it overcomes all those obstacles. You can find a PDF of this exercise as well as any other Out of the Box Geological Lessons at my website here. So here we go.
Step 1: you need Play-doh in at least 3 colors. I purchased a box of 16 and combined like colors to get enough to work with. Play-doh mixes rather well with a little work. A rolling pin and a knife. I prefer something sharp so the lines are clean.
Step 2: Roll out each of the colors. Try to keep them thick and about the same size.
Step 3: Stack the layers together.
Step 4: Trim the edges so you have a nice neat rectangle.
Making sure the layers are thick enough. I found that if you roll the layers after they have been stacked to make the surface area larger causes a real big head-ache when trying to get the Play-doh apart again. 
Step 5: Make your folds. I found that making a syncline with 2 anticlines on the outsides help make the plunging syncline produce the best structures. It also saves time on making different models.
Step 6: Non-plunging folds. Cut clean across the top creating nice parallel bands. 
Step 7: Plunging folds. Cut at an angle across the fold. I found the best plunging syncline is produced when you cut across from the bottom corner to the top back corner as shown in the picture.
The direction of plunge in down in the picture. It corresponds to the right side in the previous picture. 
Another view to show the front anticlines and syncline.
