Build a DIY Spy Microphone: The Acoustic Telescope - jpralves.net
Eavesdrop from a Distance with This DIY Parabolic "Spy" Microphone « Hacks, Mods & Circuitry :: Gadget Hacks
Amazon.com: SpyX DIY Listener - Listen In On Secret Conversations! STEM Educational Science Kit To Make Your Own Real-Working Spy Listening Device. Do It Yourself Electronic Spy Toy Gadget : Toys &
SpyX DIY Spy Listener – ShenanigansToys
SPY Bluetooth Microphone | Hackaday.io
How to Make a Spy Microphone: The Acoustic Telescope | PCB | Maker Pro