Have you ever seen such "green soap" known for its hollow centre which prevents wastage? Personally I do not think these are helpful because there is still wastage when the bar breaks.
An easier way would be to wet your finishing bar of soap...
...and slap it onto a wet bar of new soap. The two pieces should stick together when you next shower!
For hand soap, you can use refills of body soap, and dilute it with water.
Invest in a foaming soap bottle...
...which will produce foaming soap!
For toothpaste, after you think you're done squeezing the tube...
...cut up the tube, and use up the remaining toothpaste!
The creator of this guide has not included tools