I put my slivers in a net pouch designed for that purpose., It's kind of like a body puff/scrub. (Yes it's made of plastic.) I bought one at Target, and the second one at CVS.
When I was about 8, I had a mold designed especially for making a bar of soap from scraps. I LOVED that thing. I asked for it for christmas and my mom ordered it from some catalog.
I'm pretty sure it was the Miles Kimball catalog, which, of course, is now available online.
http://www.mileskimball.com/mileskimball/default.aspx