Handy mirrors and gratings for atoms and molecules would open new frontiers in matter-wave optics with neutral particles. The realization of such components for atoms and molecules, however, has required sophisticated electromagnetic fields, nano-fabrication, or particle cooling, because of their inherently short wavelength and strong interaction with a surface. We demonstrate that reflective gratings designed for photons can work as a grating or a mirror for atoms and molecules of a thermal energy when used under grazing incidence conditions. The matter-waves of He atoms and D2 molecules are reflected from various gratings that are easily fabricated or commercially available. We find out the critical factors affecting diffraction peak widths and efficiencies. Our analyses imply that quantum and multiple-diffraction reflections occurring at the grazing incidence conditions are the underlying physics allowing optical square-wave and blazed gratings to function as a grating or a mirror for those particles.