On a number of occasions I've toyed with the idea of getting some kit and learning to splice but I've never had a big enough need for it, given the level of investment needed.
I suspect I may not be alone.
Which leaves me wondering - is there anyone who has the skills and some time, who would like to put together some tapered vang control lines? I'd be happy to pay a fair price for the work involved - and there might be a queue of customers!