I am interested in doing this right. The way is likely to make a piece on a 3d printer, make a silicone mold, then cast the part in silicone or best suitable polymer and glue it on. Or you can do a vacuum casting directly onto the cable, if the resin is sticky enough.
Silicone molds are the magic for making complex parts, if you chose the durometers right, you can pull one part out of another part , in the fashion of 'birth', that is non-damaging deformations occur in the mold during extraction, allowing you to cast something along the lines of 'fake grape bushel'. If the mold was stiff, you would never extract such a structure.
You can also use a spring, possibly in combination with the taper you built.
The 'direct cast on' option would require someone to give a known good source of a castable material that is suitable for this, sticks to cable too. Otherwise.. its made with a plastic extruder and thats too hard core