Abstract: Provided are molds comprising a substantially concave portion, and a cap portion that is configured for removable attachment to the substantially concave portion and comprises a mandrel formed from a substantially rigid material, wherein the cap portion and the substantially concave portion, when attached, define an internal space having a three-dimensional shape. Among other benefits, the disclosed devices and methods of using such devices provide more uniform and repeatable compaction than conventional molds, and can be used to produce compacted structures having more dimensionally accurate and repeatable surface features, thereby yielding a better, more optimal near net shaped part.