This is a cable cam mount assembly designed to enable your GoPro, Sony or other action camera run across a a tensioned line.
The design consists of two wheels and a body made to fit regular “608.” ball bearings with an 8mm core, a 22mm outer diameter and 7mm width. These ball bearings a widely used on skate board, roller skates or kick bikes. The assembly also consists of a small clip used for safety and a GoPro-style mount.

Edit 2015-05-29
Made some small updates to the design. I made the base the same width as the camera mount. I also made the safety clip more secure by snapping around the corner of the base.

Tip!
Use a piece of rubber foam piece on the end of the line as a break/dampener.