Builder Uses Magnetic Imager to Create a Hidden Secret Gesture Lock

A maker inspired by classic lock-picking stories has built a hidden lock using a magnetic imaging board instead of traditional keys or standard RFID cards. Standard magnetic locks open with any strong magnet once their location is found. To improve on this, the builder used a special sensor tile that reads both the strength and direction of a magnetic field at high speeds.

The system relies on a small hardware setup. An 8-by-8 grid of sensors detects a magnet moving by hand across the surface. A small microcontroller processes these readings. If the movement matches a pre-recorded secret gesture, a servo motor moves a beam to unlock a wooden box. A camouflaged Celtic knotwork pattern on the box helps guide the user’s hand without revealing the sensor’s exact location underneath.

Using magnetic fields also allows for added physical security. Unlike radio frequency systems, a magnetic lock can be entirely shielded behind metal sheeting to block external detection tools. However, the current prototype has limitations, such as a reliance on internal battery power that could trap items inside if the power fails completely.