If you appreciate Pi, you'll surely be able to appreciate this instructable. Although I doubt most people are going to have all of the equipment and software sitting around their house, I thought posting the exact methods used would be of interest to the instructables.com community. The most important thing is to enjoy Pi Day and appreciate the beauty of Pi.
Step 1: How to Make Your Pi Pie
I've pictured the unique steps involved in my creation. You can certainly use variations in recipe, ingredients and preparation methods to suit your needs. I'd recommend you stick to your favorite recipe and prepare the apple slices and crust as described below. NOTE: Specific instructions for setting up files, as well as details about the equipment used, are included in the next step (if you are interested).
A. Cut your apples (about 6-8 medium apples or 6 cups of cut apples) to desired thickness with a knife.
B. Cut apple slices in the laser to allow kids (and adults) to enjoy discovering Pi in their pie later (Diagram 1).
C. Mix cut apples with about 1 tablespoon of lemon juice, 2.5 tablespoons of all-purpose flour, and 1/2 teaspoon of cinnamon. Let this mixture sit while you prepare the crust.
D. Prepare pie crust in laser by "etching" 314 digits of Pi into the crust (Diagram 2). NOTE: I used two "passes" of the laser to darken characters, which you can see in the picture).
E. (optional) Appreciate your fine work in better lighting (Diagram 3).
F. Use an Exacto knife to remove the Pi symbol and a few well-spaced center holes of zeros (and 6, 8, and 9 if the zeros aren't spaced evenly) for venting during cooking (Diagrams 4 and 5).
G. Place bottom crust in 9" pie pan and fill with prepared ingredients.
H. Cover filling ingredients with pie crust top, bind crust top and bottom with a little water and pressure, and trim excess crust (fully prepared pie shown in Diagram 6).
I. Place in oven a pre-heated oven (425F) with something to catch any juices that may flow out of pie pan (Diagram 7).
J. Cook for 30 minutes before reducing temperature to 350F and cooking an additional 30-45 minutes or until crust is perfectly browned (Diagram 8).
K. Take that Pi Pie out and appreciate your work (visually) before appreciating its taste (Diagram 9).
L. Cut and serve. Make sure you encourage kids to play with their food and try to find Pi in their pie.
If you care to see how I created the digital files, please continue to the next step. Otherwise, I hope you enjoyed this instructable.