I’m not sure what your trying to make for a cable but the best idea would be to start with something already complete.
Don’t bother trying to make the small end for the carb those are so small. Find a complete cable cut it to the length you need on the twist throttle side.
Park makes a tool to recrimp a new metal cap onto the cable housing & luckytwo stroke did sells Knarps that you solder into place instead of a set screw. Maybe if you buy a brass knarp you can solder it.