What a strange question for the toilets catagory!.
Toilets catagory means 'What's wrong with my toiilet or my cistern is over flowing or toilet bowl fills up, that sort of thing.
Howerver questions like this or that haven't a catagory I usually type in google search engine to see what comes up.
Don't know but just type in the google search 'How to make soap from left over bits somethings sure to come up.
Haven't tried yet but www.howtodothings.com search how to makes liquid soap from left over bits
bob
November 2009