YouTuber Robert Murray-Smith has built a mechanical model of a coupled flywheel-spring mechanism called Dominant Flywheel. The design is based on an idea from Barely Weak and demonstrates the interaction between a flywheel and a spring.
As Murray-Smith explains, a flywheel stores energy in a rotating moment of inertia much like a coil. When it decelerates, the flywheel releases the energy as momentum to the spring. Conversely, the spring accelerates the flywheel again through its restoring force. This creates a mechanical oscillation between the two components.
For his model, Murray-Smith designed the necessary parts in Tinkercad and then 3D printed them. A weight plate serves as the flywheel, and a chopper as the spring. The components are rotatably mounted via ball bearings and spacers. Magnets as counterweights can be used to tune the oscillation.
In a video, Murray-Smith demonstrates how the model works. A push causes the flywheel to rotate, and the mechanical vibration lasts for a long time. On Thingiverse, he offers the 3D model for free download to recreate the coupled mechanics.
It is important to note that this is not a true perpetual motion machine that could supply energy permanently. Sooner or later, every oscillation subsides due to friction. The model merely illustrates the mechanical principle of the interaction between rotating and springing kinetic energy.