A great alternative for natural sea sponges are cotton knitted or crocheted wash cloths. If you love to knit or crochet these are fun little projects, they make great gifts, and are chemical free unlike synthetically made sponges. I have been making knitted wash cloth bags that you can put soap bars into and tie shut, and they have been a great hit selling at the farmers markets this summer. With the holidays just around the corner I know that I will be knitting a few more of these wash cloths, I think they will make great stocking stuffers.
What I love about these soap bags is that when your soap bars are near the end of their use and you are left with little scraps, rather than waste that precious handmade soap, you can throw all your scraps in a knitted cotton cloth soap bag, making your soaps last a little longer.