As I began to work toward splicing my whoopie slings, I started looking into "tools" to use for making splices and saw that others were using guitar strings and a multitude of other things. While walking through a local store and looking at their fishing gear, I noticed a spool of stainless steel leader wire. All they had was some 44lb so I bought it, doubled over about a 40" piece and twisted it together, leaving a small loop in the end that was doubled. Next I drilled a small hole through thr side of a 2" long piece of a half inch dowel, stuck the twisted ends of the wire through the hole and wrapped it around the dowel. I then wrapped the dowel and wire with electrical tape to keep the wire securely in place....so far it has worked great. I would estimate the wire's guage to be about 22 or perhaps smaller and it works great on both the 1/8th and the 7/64, amsteel blue.
PS: I am thinking that a slightly larger leader wire as a single strand might work as well if not better, but so far, so good with mine as it is.