TIP: Instead of a latch needle, make a 24" loop puller from #58 wire by bending wire and pinching at the midpoint.
About 24" from tag end, insert wire loop puller into hollow center of line A for 12". Bring loop puller point out of line A and pick up line B.
Pull loop puller back out through line A, bringing line B with it, so that line B is inside line A.
Insert loop puller 12" back in line B as done in line A above. Pick up end of line A with loop puller.
Pull loop puller back out through line B bringing line A with it, so that end of line A is inside line B.
Pull ends of both lines to close splice in center. Trim loose ends, and smooth out to bury them inside main line. Finished splice is 100% strong.
This is from basils site. basil makes awesome windons and topshots.