Molecular self-assembly is the spontaneous association of molecules into structured aggregates by which nature builds complex functional systems. While numerous examples have focused on 2D self assembly to understand the underlying mechanism and mimic this process to create artificial nano-, and microstructures, limited progress has been made toward 3D self-assembly on the molecular Here we show that a helical beta-peptide foldamer, an artificial protein fragment, with well-defined secondary structure self-assembles to form an unprecedented 3D molecular architecture with a molar tooth shape in a controlled manner in aqueous solution. Powder X-ray diffraction analysis, combined with global optimization and Rietveld refinement, allowed us to propose its molecular arrangement. We found that four individual left-handed helical monomers constitute. a right-handed superhelix in a unit cell of the assembly, similar to that found in the supercoiled structure of collagen.