A method of making an object by additive manufacturing includes: (a) providing an additive manufacturing apparatus including a light source; (b) providing a carrier platform having a substantially planar object adhesion surface, the adhesion surface having a plurality of elongate wash channels formed therein; (c) producing the object on the carrier platform adhesion surface with the additive manufacturing apparatus from a light polymerizable resin, the object having at least one internal cavity formed therein; then (d) washing the object on the carrier platform with a wash liquid under conditions in which the wash liquid reaches the at least one internal cavity through the wash channels; then (e) optionally, at least partially drying the object on the carrier platform by separating the same from the wash liquid, and then agitating the object on the carrier platform to drain excess wash liquid from the object; (f) optionally, further curing the object.