Explore the intricacies of building a wireless sensor network in this 49-minute conference talk from ShowMeCon 2015. Delve into the three primary elements of sensor networks, including node and data requirements, and learn about the importance of data schema. Discover how to design an efficient grid, considering network resiliency and node placement. Gain insights into centralized data management, analytics, and data visualization techniques. Examine the role of a Bluetooth abstraction layer and understand the process of calibration. Follow along with practical examples using Python code and explore the concept of the "Harbinger" project on GitHub. Whether preparing for a hypothetical zombie apocalypse or real-world applications, acquire the knowledge to create your own DIY wireless sensor network.