We introduce an algorithm that consistently and accurately processes arbitrary intersections in tetrahedral meshes in real-time. The intersection surfaces are modeled up to the current cut tool position at every point in time. Tetrahedra are subdivided by using a progressive method, which inserts the required sub-structures step by step. A state machine tracks the topology of each tetrahedron and controls the progressive subdivision. In order to keep the state machine as small and clear as possible, each topological pattern of a tetrahedral intersection appears only once. These topological patterns are mapped onto the actual case of a tetrahedral intersection by some given transformation operations. The state transitions, which contain the specific subdivision operations, are described in a predefined lookup table, which is written in a simple script language. The handling of reverse movements and possible trembling of the users hand, as well as a recursive continuation of the state m...