Abstract: A robot end effector (100) for dispensing an extrudable substance (102) comprises a chassis (110), a static mixer (101), and cartridge bays (122), extending from the chassis (110). Each of the cartridge bays (122) is shaped to receive a corresponding one of the two-part cartridges (104). Fluidic communication between the selected one of the two-part cartridges (104) and the static mixer (101) is established when the cartridge bays (122) are rotated about an axis (190) to a predetermined orientation with respect to the chassis (110). The robot end effector (100) also comprises a dispensing valve (130), attached to the chassis (110), and a head assembly (150), comprising an inlet manifold (152). The inlet manifold (152) is configured to selectively supply compressed air from a pressure source (199) to contents of a corresponding one of the two-part cartridges (104).