A pair of talking spirit levels constructed using Arduino microcontrollers and the MPU6050 3-axis accelerometer. Though they differentiations in size, the construction and components of the two levels are virtually identical. A full build blog can be found Here.
The software is freely available for download. Version 1 is the initial release and implements the features described in the build blog above. It is available for download Here.
The below video demonstrates the larger of the two levels in operation.