1. A method of creating a design of a sketch-based eggcrate substructure for manufacturing composite parts, comprising: providing an input model from a plurality of inputs, including: providing a layout geometry; and providing a specification data structure; creating, via a processor, a resolution model of the input model, including: interpolating the layout geometry; interpolating the specification data structure; and defining the eggcrate substructure having a plurality of closed egg-cells based on the interpolated layout geometry and the interpolated specification data structure; finalizing a layout using the resolution model; and providing one or more solid components into the finalized resolution model to create the design.