Seems pretty simple but I can't find anywhere that actually says how to thin out piping gel. Can I just add water to it? I need to thin it out enough so I can add gold sequins to a buttercream cake that crusts. If you know of another way to add them onto a crusting buttercream I'm all ears :) 

i'd try corn syrup -- bur fresh piping gel should be fine without thinning it out

Just use a tiny drop of piping gel or even b'cream.  Either should hold them in place.  As k8 said,really no need to thin it out.;