Soap grafting¹ is the act of attaching an almost completely used piece of soap to a new, unused piece because it is now too small to be conveniently used but you also don't want to waste it.

如果你觉得快用完的小片肥皂滑滑得不好拿，但是丢掉又太可惜，你就可以将它粘在一块新的肥皂上继续使用，这个过程就叫soap grafting（肥皂嫁接）。

For example:

My mum always soap grafts² because she doesn't want to waste anything. Soap grafting is good.

我妈妈经常把快用完的肥皂粘到新肥皂上用，因为她不想浪费任何东西。这种肥皂嫁接是个不错的办法。