In one illustrative embodiment of a coated feeder, a coating is integrated into the structural components of the feeder. The coated feeder may include a base, ridge, and back, which may all be integrally formed with one another. The coating may include an exterior surface opposite concrete. The surface of the coating adjacent the concrete may include at least one tab, at least one linear protrusion, at least one hook, and at least one channel.

In exemplary implementations of this invention, a nozzle sprays foam, layer by layer, to fabricate a fabricated object according to a CAD model, and a subtractive fabrication tool removes material from the fabricated object according to a CAD model. The fabricated object comprises a mold or an interior form. The foam may be low-density, high strength and fast-curing. The foam may be used for large-scale 3D printing. For example, the foam may be used to 3D print molds for walls of homes. The foam molds may be left in place, after casting concrete in the molds, to serve as insulation. Or for example, the foam may be used to 3D print on site an internal form for a large wind turbine blade. The wind turbine blade may then be produced on site by depositing fiberglass on the outside of the internal form.

The present invention relates to a process of fabricating a multi-layer composite structure by 3D printing, said composite structure comprises at least one cured mortar layer formed by curing of a mortar composition, and at least one polyurethane layer formed by polymerization of a first polyurethane forming composition, wherein said mortar composition and said first polyurethane forming composition are dispensed individually and simultaneously via adjacent printing nozzles. The mortar composition is optionally modified by a second polyurethane forming composition.