Print with the medium heat resistant material of your choice 0.1mm layers & 0.4 nozzle recommanded centrifugal fans sourcing : http://www.mouser.fr/Search/ProductDetail.aspx?qs=%2fW4LtXOBxKsfL3eA88psUg%3d%3d - Reuse the 4 M3 stock UM fan duct screws - The centrigugal fans don't need to be screwed, just to be clipped, - Reuse the stock UM fans plugs by welding the wires to the new fans, what I done. ( when cutting wires keep 20mm wires on the stock fans, they can still be useful) - Or source & add new " Cables 120mm long, plug JST XHP-2 " Anyway, careful to respect the polarities - the fan duct can be tilted by rotating on its hinges for an easy access to the Olsson block - recommanded use aluminium tape sticked inside the central portion around the nozzle hole