What Can I Do With My Leftover Single Shoes?

Keeping in mind that you really do not like to waste anything,
First thing that can be done is to keep the shoes together for
sometime so that they stop feeling lonely in absence of their mates.

Now as they are in excellent condition, starting with the sandal, it can be
used for fixing those rickety tables around the houses which keep rocking every time you sit with a guest for a nice evening meal. Your cell phone keeps lying here and there, so you can make a cell phone stand out of your sandal, that would save you from finding it every time it rings. The loafer can be used for making an innovative flower vase and finally the high heel can be used as a stylish paper weight or as a hammer for
driving nails and breaking objects. It can also be used to plough the garden. It can itself be hung on d wall and used as a hanger or hook
where you can hang your most favorite canvas.

And apart from the stylish paper weight high heel, the unfortunate
pair of sandal and the loafer can we worn on the Halloween.

The donation idea is a good one.  If for some reason that doesn't
pan out, you could fill the high heel and/or loafer with plaster (or
some other heavy substance) and use them as doorstops.  Or they
could become dog toys.  Donate to an artist.  Put them on
Craig's list.  Are they all for the same foot?  If not you
could wear one of each to work for a while and see how long it takes
people to notice.

A niece's high heal huh? Surrrrrrrreeeeee... Uh huh....lol... I agree with Nascarnut's answer... Check with a prosthetic maker.. They might know where there might be a shoe exchange for people who have lost a foot. I have a friend up in Michigan that has one leg, and he gets his shoe from an exchange. They also match people up with others that have different sizes of feet and are the opposite of each other( did that make sense) If all else fails... You can make planters out of them. Hugs