[Best material for a working prototype?]

It will be used outdoors so the elements are a concern. 

[Best material for a working prototype?]

I have a part I'm needing to print.  The material must be very strong but I need it to have a slight flex for a rope to release through. Picture is just an example I pulled from Thingiverse.

It will be similar to how this works.  I am using an Ultimaker S5 Pro Bundle

[S5 attempting to Print wth Carbon X Nylon]

Hello,  I am having an issue with failure to extrude.  I am using Carbon X nylon gen 3 with a new CC .6mm print core.  I began the xy calibration for the new print core. It extruded the carbon X for loading but nothing during the calibration print. so I just try to start a print to see if it would extrude , I get a message saying to load carbon x into extruder 1.  It is loaded, i also moved to a different bay with no success.  Any help would be appreciated