Tree09
Treehouser
You can make a fid for 3 stand out of a chunk of half inch pipe, just cut the end at a 45 degree angle to make it easier to insert. Tape the ends really well or use constrictor knots, and when you do your tucks make sure to twist it to keep the tight lay. The problem with synthetic ropes is that the fibers don't have memory, so you have to work to keep the right twist tension a bit. If you are trying to learn how to splice it first, i strongly recommend going to a hardware store and getting 20 feet or so of Manila. The individual strands will have a memory to them and they keep their shape better, so it's easier to learn on.
I personally use a crown knot to start the splice when I'm doing a ring, so you will need to practice that as well, usually taught by doing a back splice. Believe it or not splicing 3 strand is still taught in our fitter apprenticeship, they view it as that necessary for tag line use and light rigging. We learn the clove hitch, bowline, pipe hitch, bucket hitch, to never use a square knot, eye splice, and back splice.
I personally use a crown knot to start the splice when I'm doing a ring, so you will need to practice that as well, usually taught by doing a back splice. Believe it or not splicing 3 strand is still taught in our fitter apprenticeship, they view it as that necessary for tag line use and light rigging. We learn the clove hitch, bowline, pipe hitch, bucket hitch, to never use a square knot, eye splice, and back splice.