To determine the shape and size of nanoparticles and other nanostructures by NMR is very challenging. This information is obtained much more easily from microscopy or scattering data, for instance small-angle scattering patterns of oriented samples. Even for unoriented systems, small-angle scattering curves I(θ) or I(q) contain information on particle shape and packing. To take full advantage of this approach, we have introduced an algorithm to calculate the I(q) curve from any model defined on a cubic lattice with periodic boundary conditions. The approach is based on numerical 3D Fourier transformation as used in multidimensional NMR. [J. Appl. Cryst., 2007] As a complementary approach to determine the shapes of nanocrystals, we are also simulating wide-angle diffraction patterns.