The ‘GetItRight’ Digital angle finder is available from the GetItRight ebay shop for about £25.

It comes apart easily. The main blade is held in place by two small Allen screws the other parts use countersunk self tapping screws. (take care when removing the battery compartment as the battery contact will catch on the aluminium extrusion ).

Inside the electronics are split onto two modules:

A capacitive angle encoder, which plugs into...
An LCD driver module via a 6way ribbon connector. The LCD module carries the  switches and battery power terminals

The encoder has its own ASIC and is approximately 45mm diameter.

The brass rotor appears to run in a small (ball?) bearing pressed in to the plastic housing.

The back of the LCD module shows a few unused options, such as bleeper and backlight (?).

Near the encoder connector are some interesting test pads that connect directly to the encoder module connector.

SCLK, SDA and SEA are the clock, data and data enable output signals from the encoder

The upper trace is the SEA signal the lower trace is the SCK signal

SCK (top) and SDA. The 24 bit clock is not symmetrical, the fourth pulse is longer; perhaps signifying that the data is in six four bit nibbles (?)   

The angle finder is a digital protractor . The large LCD displays the angle in degrees to one and a half decimal places.  The display can be zeroed on a level surface, to provide a 360 degree absolute measurement, or zeroed at any angle to give a relative reading (without changing the absolute setting) . It also has a display hold and a spirit (bubble) level for vertical zeroing.

The quoted accuracy is 0.05 degrees, some quick tests using a sine-bar and surface plate seemed to confirm the accuracy.