A recipe calculator app is built using Twilio Programmable Messaging to send the total cost of ingredients in a user-submitted recipe to their phone number. The app allows users to input the price, weight, and unit weight of each ingredient and receive an itemized text message with the costs. The code includes PHP files for the form submission, Twilio SMS client, and success page. The project utilizes Bootstrap for styling and CSS for design customization. Users can test the application by submitting a recipe and receiving the cost of ingredients via SMS.