What a waste if simply dispose the used eye shadow palettes...
Here is a hack to get rid of your worry!
Combine a lip balm and eye shadow in brown colour
Have fun making your own shading stick!

1. Take whole content of lip balm and melt it
2. Add a rich colour(brown) into it.
3. Heat to melt then blend it.
4. Pour the mixture back to the lip container then freeze it for an hour, done!