An injection mold device comprises a first matrix attached to a movable platen and a second matrix attached to a fixed platen. A multiplicity of first cavity units are attached to the first matrix. A multiplicity of second cavity units are provided for selective removable attachment to the first matrix during a mold-clamping state and to the second matrix during a mold-opening state. A self-holding device is associated with the first matrix for maintaining a clamping force between the first cavity units and the second cavity units during the mold-clamping state. A mold-opening device is associated with the second matrix for removably attaching the second cavity units to the first matrix in the mold-clamping state and for removing the second cavity units from the first matrix in the mold-opening state.