An end effector for printing ink on a surface is disclosed. The end effector comprises a primary block comprises a primary-block body. A plurality of primary-printing modules are coupled to the primary-block body and translationally moveable, via a corresponding first actuator. Each one of the primary-printing modules includes at least one printhead which is adjustable, relative to the primary-block body. The printhead may be adjusted by at least one of a second actuator, configured to rotate the printhead about a first axis, or a third actuator, configured to rotate the printhead about a second axis. In some examples, a fourth actuator is configured to rotate at least one printhead, relative to at least one other printhead, about a third axis. Additionally, at least one trailing block can be coupled to the primary block so that the at least one trailing block is movable relative to the primary block.