I made one using the plans from Sailrite and a standard household sewing machine with heavy thread and needle. This did push the machine to the limit but it all worked out.
http://www.sailrite.com/PDF/Spinnaker_Sock_Instructions.pdf
I have only used the gennaker three times, it seems like whenever we have been out since I made it last summer its either super light and shifty or blowing like crazy. The spinnaker/gennaker halyard on my 30+ comes out of the mast right above the forestay, so when the snuffer hoop is raised it tends to bind on the furler a bit. Its not an ideal setup, but with only three uses, I have not had a chance to properly sort it out yet. I probably need to not raise the halyard quite so far. It was very nice to easily snuff the sail last time we used it when the wind suddenly picked up out of nowhere.
I don't seem to have many photos of it, we were probably too busy trying not to run over the sheets and keeping everything from getting tangled up.