An exemplary inventive molding device includes two mold components characterized by matching rounded-star shapes. Each mold component includes eight congruent rounded-tip projections and eight congruent apertured sections separated from each other by the projections and describing a ring shape. The projections correspond to the equiangular points of a star. Each section has a medial hole and is interposed between and connects two projections. The mold components are joined so that their respective projections and holes are even with each other and fasteners are installed through the holes. Appropriate introduction and curing of a castable material inside the joined mold components produces a flexible device suitable for use as part of a biomimicking soft robot.