Another idea for an adjustable hex wrench. The sliding part is actuated linearly by squeezing the handles together. This allows the slider to conform to the outer diameter of the bolt. The largest bolt is only limited by the size of the opening in the wrench. Can be printed with various scaling.

View the full write up below:
http://www.inventionfactory.xyz/2016/02/adjustable-hex-pliers-grip.html