There is a special place reserved in heaven, I am certain, for folks who figure out a way to not throw stuff away. My wife may quibble. In any case, soap nubs - those things left after a bar of soap is no longer able to be held reliably in hand - have been a particular sore point ever since I learned that there is a company in India that pays people to scrape the outside layer of hotel soap bars away so that the bars may be sold at discount and re-used by people who can't afford to buy new bars.
We started saving soap nubs thinking maybe we could use them to keep deer off our fruit trees. That didn't work. But it did show us how many nubs we generated! Now, here is what we do. You will need:
"Melt and pour" type soap (available online)
Soap molds. We use silicone molds.
A double boiler
At some point, we will try to offer these things on our site. In the meantime, you can find all of this stuff online.