Wearing gloves, wash and dry your peppers and cut off the stem of each pepper.
Place your peppers on a foil lined rimmed baking sheet in a single layer and place them in the oven. You can do several trays if you wish.
After about 3 hours, shake each pan and rotate for even drying.
At the 4 hour mark, check to see if any of the small peppers are dried. They will begin to crumble when touched. Remove any peppers that are completely dried and continue to dry the others to the oven to finish drying. (approximately 4-6 hours)
Once your peppers are completely dried, remove them from the oven to cool.
Place the dried chilies in a food processor or grinder and pulse until you get the desired texture of the red pepper flakes.
Store in an air tight container.
Approximately 50 cayenne peppers will yield 1 cup of red pepper flakes.