A method of constructing 3D Earth models from a suite of 1D profiles is demonstrated using Delaunay triangulation. Accurate crustal models are required to correct for crustal contamination in seismic tomography of the mantle and can be used as starting points for higher resolution tomography of the lithosphere and asthenosphere. Using a simple input data set, 1D vertical profiles, provides for rapid prototyping, model building, and modification. Any structural length scale in the final 3D model is possible using this method through precise placement of 1D profiles and triangulation. Collections of layers within the 1D profiles are grouped and identified by keys, called superlayers, allowing for 3D discontinuities and variations along these important interfaces. The method was applied to the Gulf Extensional Province and Baja California regions to account for the laterally discontinuous crustal variations during a tomographic inversion for mantle structure. Use of the 3D model and appropriate regional crustal wave speeds minimizes wave‐speed variations in the tomographic model and assists interpretation of the final model.