Richard,
I have not read all of the above posts but I started to write this a while ago so thought I'd post it anyway.
I've made up bicycle cables but not motorbike ones. This is how I would make a clutch cable. First of all just plan and fit the outer cable, making sure that it has a nice, easy run, taking into account full lock steering movement.
For the inner, attach the top nipple and put it into the handlebar lever. Grease the cable and feed it into the outer, not forgetting the adjuster at the gearbox. The adjuster should be screwed well, (but not fully*) into the gearbox abutment to later allow for the outer to be lengthened, which has the same effect as shortening the inner if/when it gets stretched. Make sure the inner cable is pulled properly tight and mark where the gearbox nipple needs to go. Cut the cable; thoroughly clean the grease from the cable strands and the nipple. Slide the nipple on and splay the ends into the nipple countersink then solder or braze the nipple into place. Adjust if necessary, (*by screwing adjuster into the abutment) to give a small, (1/8") slack of movement.