Building a crystal radio requires essential components such as an antenna, coil, capacitor, diode, and high impedance earphones. Many parts can be sourced from broken electronics or local hardware stores, with some users suggesting the possibility of constructing a fully homemade version known as a "foxhole radio." Online resources and kits are available, with RadioShack mentioned as a potential supplier, though some users report dissatisfaction with certain online vendors. The discussion emphasizes the educational value of building crystal radios and encourages experimentation with different configurations. Overall, participants share tips and resources to support the construction process.