Any EMI interference can be resolved by putting a single folded sheet of aluminum foil flush with the motors behind the plastic. and another flush with the rear of the fan in front of the plastic. which makers 2 layers before the fan let me know if you like this thanks! This is the first of its kind.... a rear facing turbo style fan used on a Wanhao duplicator 4 No other fan design is like this. and gives complete access to see on the front while blowing lots of air from behind. it uses no screws, it clips in. its a tight fit. it might be easier to unscrew the extruder assembly from underneath, remove it out the way then clip it on and put the 2 screws back in... but i did it without. i printed it on its side with support using simplify 3d. you will have to mess around with supports. but you will get there. i used a fan like this one from ebay. http://www.ebay.co.uk/itm/2-Pin-Connector-Brushless-DC-24V-0-15A-Turbo-Blower-Cooling-Fan-/191037705258?pt=Computing_ComputerComponents_Fans_Heatsinks_SR&hash=item2c7abc0c2a Flashforge prototype version included, thanks for luke to new dimensions