A robotic pen includes a computer numerically controlled machine having a multiaxis stage for mounting a workpiece, and a cooperating elevator which translates relative thereto. The trocar cannula and trocar housing are mechanically interfitted to form a trocar sleeve, wherein at least a portion of the trocar cannula sits within the housing member base with the housing member cover sitting over the trocar cannula for securing the at least a portion of the trocar cannula within the housing member base. The LEDs are located on a single, two-sided printed circuit board, which reduces the assembly costs and the size of tail light, as well as the complexity of assembly.