The secret to nipples?

While recently making some new control cables for my Triumph TRW I decided to reuse the original nipples and, when they were unsoldered, I discovered the inner cable was very neatly made into a mushroom shape prior to the nipples being fitted.

Over the years, when making cables, I have “fanned” out the inner cables before soldering on the nipple but now my question to the readers is – is there a technique to produce this “mushroom” or is there a tool to make this very neat and obviously very secure fitting?

I should add I am 99% certain the cables were original factory fit.

I have attached some images (not very good but hopefully good enough to get the question across).

It would be appreciated if, perhaps, you could find a space in OBM to present this question to the readers.

Like you John, I’ve simply splayed the strands of the cable apart before applying solder (usually unsuccessfully), but maybe some of the OBM readership can suggest their own techniques? – Ed.