Paper Plate Marble Track - use heavy duty paper plates. cut sections, then overlap and tape the ends together to from one long twisting route. For supports, you can also use TP tubes in graduated lengths. To make a tunnel through a support, just cut an opening in it. Attach plates to tubes with glue dots.
"Animated diagram showing the operation of a tuned circuit (LC circuit). The capacitor stores energy in its electric field E and the inductor stores energy in its magnetic field B (green). This jerky animation shows “snapshots” of the circuit at progressive points in the oscillation. The oscillations are slowed down; in an actual tuned circuit the charge oscillates back and forth tens of thousands to billions of times per second."
There are lots of schemes that oscillate in the 40 - 120MHz range, but they usually use LC circuits, varicaps, pin diodes, controlled by 0 to 30V voltage source. This makes the devices more complicated and a special correction of the output levels of the signal is needed. The proposed design offers a wide range of frequency tuning, stable output levels and is powered by a +5V supply.