A device for dispensing a mixture of at least two fluids is disclosed. The device has a plurality of cartridges that each contain a fluid. A flow channel communicates with each cartridge. A valve adjusts a mass flow rate of the fluid drawn from the corresponding cartridge. A manifold has a mixing chamber and a plurality of inlets that each communicate with one of the flow channels. The manifold has a spring and a seal that covers the inlets. A piston is between the seal and the spring. The spring is moveable between an extended position that positions the seal to substantially and simultaneously close the inlets from the flow channels and a compressed position that positions the seal to substantially and simultaneously open the inlets to the flow channels. A dispensing pump communicates with the manifold and draws fluid from each of the cartridges. A nozzle dispenses the mixture.