asvjerry - the best way to apply the ingredients is in very thin layers. I have made sandpaper samples with up to a dozen layers, and they work better and better as you add layers. But my experiments show that certain ingredients work best when applied in a layer adjacent to certain others. For application to cables and chassis etc., more than 2 layers is not really practical, so I usually apply the semiconductors, conductors and superconductors (germanium, polyaniline, graphene) first. Safe, non-conducting materials are added last.
I use a brush. Thinning with water is good.
Dipping has not worked well for me.
I don’t really think the formula would work for speaker cones, but I haven’t tried it. I see no reason that it should work, apart from providing a measure of EMR protection for the entire speaker circuitry. There is also a spectacularly successful way to apply the material to any surface. It is called nanotape, and it really is incredible.