The invention includes a core-and-shell dosage form or unit in which the core contains API and in which the shell substantially governs the release such as by controlling diffusion of API through the shell. The shell may comprise a release-blocking polymer, and particles of a release-regulating polymer. The shell may be substantially impervious but the release-regulating polymer may become suitable to allow diffusion through it when activated. The core may include a buffer region between the shell and the API-containing portion of the core. The dosage form may include multiple units. The dosage form of the invention is capable of providing a release profile whose time scale can be adjusted by adjusting powder composition, and which may be approximately zero-order release. The invention further includes methods of manufacturing such a dosage form, such as three-dimensional printing.