Described herein are stereolithographic methods for preparing 3D objects comprising hollow regions and/or multiple materials. In certain embodiments, the methods comprise applying a blocking composition to fill hollow regions in the 3D printed object. In certain embodiments, an absorbent is applied to dispense material into the 3D printed objects and to remove unwanted resin from the hollow regions. Additionally, in certain embodiments, the modular stereolithographic apparatuses described herein contain an invertible, double vat, which enables users easy access to multiple materials throughout the 3D printing process.

Tooling packages for mold building structures, mold structures, and methods of making mold structures are described.

Described herein are stereolithographic methods for preparing 3D objects comprising hollow regions and/or multiple materials. In certain embodiments, the methods comprise applying a blocking composition to fill hollow regions in the 3D printed object. In certain embodiments, an absorbent is applied to dispense material into the 3D printed objects and to remove unwanted resin from the hollow regions. Additionally, in certain embodiments, the modular stereolithographic apparatuses described herein contain an invertible, double vat, which enables users easy access to multiple materials throughout the 3D printing process.