I have previous knowledge of how to taper dowels. I believe the technique is to use a hand plane or a sanding block to remove the wood from the end, very sparingly as you rotate the dowel simultaneously on a flat surface like a tabletop. Almost like whittling but removing minimal amounts of material at a time.

The rigging is, however, another question. Make sure you have some precision tool available such as tweezers and locking hemostats (like surgeons use). I find these indispensible for working with rigging.