The first idea is to make a cube when shaked hard, the sound would be walnut and when shake soft, it turns from walnut to water.
This will be using Adafruit 9-DOF Absolute Orientation IMU Fusion Breakout - BNO055
Second idea is to build a cube for fishing. The fishing tank use a Strain sensors and a motion sensor inside to detect whether this gesture will catch a fish or not. It is also possible to catch a garbage. I am just curious about how sensor can read the tiny feeling of fishing.

Third idea is to show the fireworks that is only alive when giving out to the air. Maybe using acceleration sensor and some touch sensor to detect whether a human is touching the cube or not. The continuous act of throwing it to the air would result in a gorgeous firework.