An example technique for generating slice data from the tree data structure representation of a three dimensional (3-D) object can include obtaining a shape specification of the 3-D object and obtaining a material specification of the 3-D object. The example technique for generating slice data from the tree data structure representation of a 3-D object can also include merging the shape specification and the material specification to create a tree data structure representation of the 3-D object. The example technique for generating slice data from the tree data structure representation of a 3-D object can also include generating slice data from the tree data structure.