I designed 3 different air ducts for cooling the electronic board of the ultimaker original plus. Radial fan: The air duct has the dimensions of 40 x 20 mm at the fan outlet. For installation, you need two M4x40 screws and nuts. Axial fan with diameter of 40 mm: For installation you need eight M3x15 screws an two M3x15 screws with nuts. Axial fan with diameter of 50 mm: For installation you need four M4x16 screws an two M3x15 screws with nuts.