How do you efficiently bend thick wires like 10mm to 16mm, say you want to link two neutral bars together so you need a 16mm bridge, that stuff is impossible to bend at 90 degree angles without actually bruising your fingers. I tried pliars but those damage the insulation. There must be a more efficient method 

Good old fashioned pliers works or alternatively a long nose pliers also works. The insulation will not damage. Begin with the start point & make bends as necessary to work your way to the end point. 

A lot easier is to use panel flex wire instead of gp wire. It works a lot easier for a little bit of extra money.