Making figures out of dough to teach the handicapped, then getting rid of them

There is nothing wrong with what you have mentioned about
making shapes of inanimate things, even if they are made out of flour or
dough, in order to teach the mentally handicapped how to move their fingers.
But it is better to make some use of the flour after that, even if it is by
drying it and giving it to animals to eat, so as to preserve the blessing
and not waste it. But if you cannot make any use of it, then there is no sin
in throwing it away and getting rid of it. 

Some scholars have stated that it is permissible to use some
kinds of food in shampoo and similar things that are used for washing the
face, and it is known that these things are washed away with the water and
no further use is made of them. 

The scholars of the Standing Committee were asked: 

In the marketplace I see a kind of shampoo that the grocery
store owners say is made with eggs, and another kind that contains lemons.
Is it permissible to wash with them? They replied:  

It is permissible for you to wash with shampoo and water,
even if it is mixed with lemon or eggs, and to wash with soap and the like
with water, to help remove dirt.  

Fataawa al-Lajnah al-Daa’imah,
24/108 

And Allaah knows best.