Classical methods to build stratigraphic horizon surfaces in geomodelling are based on spatially constant geometric or statistical regularization criteria. However, mechanical deformations generating these structures may localize deformations differently based on mechanical heterogeneities. We propose a geomechanical method to build a 3D stratigraphic model from 3D horizon points (from seismic data or interpretive cross sections). We use mechanics-based restoration, based on finite element elastic computations, to flatten the points and build the interpolating surfaces. Restoration boundary conditions are transferred from the horizon points onto a meshed volume using barycentric coordinates. After each restoration step, a flat surface defined by the restored points of the uppermost horizon is built. Reversing the restoration vectors yields the deformed interpolating surface geometry.