Jetslide JSB-10 Brass 66

There seem to be differing opinions as to how easy this is to use, but in my experience, it only takes little practice to make it work – and it works fast, in terms of switching it "on" or "off." (Also, the technique and results will be slightly different whether you have it on your middle or ring finger.) Admittedly, I have only tried it briefly on a regular guitar, and mostly applied it to a three-string cigar box; search "JetSlide cigar box guitar" and you can decide for yourself if it seems workable enough for your needs. That said, it sounded beautiful on the regular guitar too... it might not be for everyone, but I certainly would warmly recommend the JetSlide!