Thread: how to duplicate tapered legs

Here's some dimensions
The narrow part of the shaft and the head, must be very smooth so that the lace thread doesn't catch on the wood.

The bobbins my sister uses are more in the shape that Dave posted



The main elements of a bobbin are:

a head and neck (where the thread will be attached);
a main shaft, body or shank (held by the lace-maker) and
a tail end strung with beads to add weight and stop the bobbin rolling around on the lace pillow, and to help identify which thread is which.

the ‘neck’. A long length of thread will be wound the neck and stored there, just gradually unwinding as lace-making progresses.This stored thread is held in place by a slightly bulbous knob atone end of the neck (it is the start of the bobbin’s ‘head’) and by the thicker main shank at the other end.In practice, necks vary in length. Longer necks could carry more thread which was useful when either a thicker thread was involved or if a bobbin was being deployed as a ‘worker’. Worker bobbins act like shuttles: they move over and under the other warp-bearing bobbins. The latter,the majority, are called ‘passives’ since they just ‘hang about’ for much of the time, a role that leads them to require much less thread.
Immediately above the knob there is a little recess (the ‘short neck’)round which the working end of the stored thread is hooked and gradually unwinds. It is important that the head of a bobbin is not chipped or broken - if it is, a working thread will easily slip off.