As part of my organization streak, I emptied my mending basket.  The mending included replacing an invisible zipper in a store bought skirt.  Invisible zippers are the easiest kind to put in, but I really dislike the cheap plastic feet that are sold next to them.  Mine slid all around and made for a really sloppy installation.  I hot glued it which worked for a bit and then broke the foot altogether.  Searching for a cheap alternative I found my piping foot to work perfectly.  I moved my needle position until it stitched right in the crease and had the nicest looking zipper I've ever put in.