Provided is a method of forming a shaped structure. The method includes coupling a first section of a mold to a second section of the mold such that a mold cavity is defined, wherein a cross-sectional shape of the mold cavity corresponds to a cross-sectional shape of the shaped structure and wherein at least one of the first section of the mold and the second section of the mold comprise a soluble material; at least partially filling the mold cavity with a curable polymer; and curing the curable polymer in the mold cavity to make the shaped structure.