A 3d printed model of an old-fashioned ship’s lamp hovers just a few mm above a base board. The lamp is lit with RGB LEDs that change colour on demand.
The levitation will be provided by an electromagnet hidden in the frame above the lamp with the position detected by a hall-sensor and controlled using an op-amp circuit.
The charging circuit will provide power to the lamp through its base and the data channel will transmit the requested colour. A set of 3 sliders would allow you to change the colours. One microcontroller would read these values and convert them into a digital message, a second onboard the lamp would decode the message and change it back to a colour.