Methods for the top-down design of nucleic acid nanostructures of arbitrary geometry based on target shape of spherical or non-spherical topology are described. The methods facilitate 3D molecular programming of lipids, proteins, sugars, and RNAs based on a DNA scaffold of arbitrary 2D or 3D shape. Geometric objects are rendered as node-edge networks of parallel nucleic acid duplexes, and a nucleic acid scaffold routed throughout the network using a spanning tree formula. Nucleic acid nanostructures produced according to top-down design methods are also described. In some embodiments, the nanostructures include single-stranded nucleic acid scaffold, DX crossovers, and staple strands. In other embodiments, the nanostructures include single-stranded nucleic acid scaffold, PX crossovers and no staples. Modified nanostructures include chemically modified nucleotides and conjugated to other molecules are described.