A valve that fits to Lego NXT motors. The valve works by pinching a hose shut with a piston. A plexiglass cover can be attached to secure the assembly. Can be stacked.Print and attach the NXT motor to the base object with bolts and nuts. You probably need washers or similar to have the NXT's holes leveled with the part. Attach the actuator using a Lego technic axle and add the piston. The hose can be now inserted to the slot reserved for it. Hose diameters around 10mm should work. Silicone hose has been tested, but soft PVC might work also.