Abstract: Set forth are methods for preparing encoded three-dimensional objects. Magnetic particles or particles containing compounds that emit identifiable spectra, or combinations of multiple different magnetic and/or spectral emitting particles are embedded in the 3D object during formation. The particles can be added into the build material before construction, injected in a controlled manner into the 3D object during formation or added to the surface of the object during or after formation. The embedded material allows information regarding when and how the product was manufactured and the materials used to produce the product.