To build a 40 MHz oscillator circuit, the simplest method is to purchase a canned 40 MHz crystal oscillator. If the goal is to design a circuit using discrete components, it’s important to reference appropriate textbooks and resources that cover oscillator design principles. The discussion emphasizes the need to clarify whether a pre-made solution or a custom design is desired. Participants are encouraged to share their available resources for designing the oscillator. Ultimately, the choice between a ready-made oscillator and a custom design will dictate the approach taken.