This is my version of a cable routing for the A1's extruder cable. 
( since it has caused some problems for me like tangling with the A1 )
 

The parts are constructed in a way so that they don't collapse and fall on top of the X-Axis rails, which could cause problems if the extruder moves around the X-Axis or tries to cut some filament. Apart from a 3D printer, there are no additional tools needed to assemble the cable routing. 

The cable which goes to the extruder can simply be pushed inside of the parts through the designated grooves. In order to connect the parts they have to be pushed into each other (bending them a little bit might help). Make sure that the parts are installed in the right direction (the grooves should look towards the 3D printer, not away from it), since the cable routing is constructed to only rotate freely in one direction.

The part that goes on top of the extruder can simply be attached.