The design is a simple ducted blower (radial) extruder fan which can be used to focus cooling exactly on the extruder nozzle area. The assembly uses: The photos show the assembly components and the blower fan mounted on the Wade extruder. In this case the printer is a Robo 3D The parts are an interference fit in the blower outlet or can be glued/siliconed. The fan assembly is screwed tightly to the unused screw hole on the extruder stepper motor and can be adjusted up/down. Adjust the length of the duct and angle of the copper wire to focus the cooling. To make sure the assembly moves only when you want it to, use a rubber washer(or similar) between the fan and the stepper motor. There are no other mods to the extruder assembly required and the stock fan should not need to be removed. A extra pair of light duty wires needs to be run back through the extruder loom to the Ramps fan connection terminals. Might be useful to have a switch to turn each (or both) fans on/off.