[abenedik]

You probably want to show different texture images on different sides of the box.

The problem with boolean operations is that it removes the TextureCoordinates that are needed to show the texture.

As it is written in the code comment in the BooleanOperationsSample.xaml.cs, you can use TextureCoordinatesGenerator after boolean operations are done - this can be used to apply texture coordinator to simple objects like boxes, spheres, cylinders and planes.

See also UseCases/ModelingWithBooleanOperations and Utilities/TextureCoordinatesGeneratorSample on how to use TextureCoordinatesGenerator.