3D Design: Thin-Wall Rock-Like Object

I require a 3D design for a thin-wall object that resembles a rock. This object should have a flat bottom and a flat/circular opening/door on one side, and be slightly larger than an egg. The design will be used for a prototype intended for manufacturing. Key Requirements: - The model needs to be solid-modeled/sculpted in a CAD software that can export STEP, IGES, SAT or X_T solid models (not STL, OBJ, mesh file formats). - The design should have no negative drafts to ensure manufacturability. - The main part of the object can be designed as more than one part (e.g. a top half with a bottom tray). - The door will be attached with small flexible straps for hinges; no need to design hinges, but need to keep in mind that they need to exist. - We are mainly looking for the sculping work of the exterior, but if you can complete the whole thing, that is a bonus. - The object is a functional container, specifically designed to hold solids. - This prototype will be 3d printed, but needs to be designed with injection mold manufacturing in mind. - We are using SolidWorks, but okay to work in other CAD as long as we can get the usable export files we need. Ideal Skills and Experience: - Proficient in CAD software with experience in creating solid models - Prior experience in designing for manufacturing, specifically drafts - Sculping or making organic shapes in CAD