Sailrite sells kits for various sizes of foredeck bags. I've built two with a medium powered sewing machine, and they work very well. Nice to keep hanked on sails out of lockers but protected, and always ready to yank up in case of engine failure, etc. Url is:
About the only drawback is that it is sometimes a little difficult to get the zipper started when you're leaning over the front of the forestay on a pitching deck. But all in all a great way to go.