Even after my last modification i wasn't satisfied with the noise reduction of the base fan in my Monoprice Mini Delta. I recalled what has to be cooled in the base of these printers. It's the aluminium heat spreader, that is glued on the drivers on the motion controller. That's why i designed a fan duct, that directs the airstream of a more silent 5015 linear fan directly over the heatspreader.
The duct is superglued to the fan housing, and the whole combination is fixed with 3M mounting tape on the inside of the baseplate. Its in the right position over the heatspreader when you place the ducts marked corner 2.3 cm downwards and 2.3cm right from the marked corner on the tin plate (see second photo).