The present disclosure provides methods for freeform extrusion-based additive manufacturing via a robotic arm. In specific aspects, methods are particularly provided for minimally invasive, intracorporeal three-dimensional printing of biocompatible materials. An end effector of a robotic arm includes a sharp member and a reservoir filled with a printing material. The provided method may include piercing a substrate with the sharp member. A bulb or microbolus of material may be extruded beneath the substrate surface to act as an anchor. The end effector may be manipulated to extrude biomaterial along a printing path. Periodically along the printing path, the sharp member is used to pierce the substrate surface create additional respective anchors. In some instances, the method may terminate after extruding material to form a single layer construct. In other instances, the method includes forming one or more layers on top of the initial base layer anchored to the substrate.