A fan duct that allows you to mount a 40mm fan above the extruder mount on the rostock-mini platform. Air is blown down over the top of the extruder to keep the heat down at the bottom where it belongs!
I suggest you try setting your cooling to 25% for extruder cooling (at 100% my extruder couldn't maintain 185 C!). It can cool a print job if you run it at 100%. See a video of me printing my C9 bulb cooling required test part here:
Print the STL. If you print the one with the wire slot cut out of it, you can open the duct up and slide it over your bowden tube and wires. If you printed the solid one without the wire slot, you will have to disconnect your bowden tube and wires and slip the duct over them before reconnecting them.
Use four M3 screws (I used 16mm length) to mount it to the platform (from the bottom) via the four extra holes. Use four M2.5 screws (I used 16mm length) to mount a 40mm fan to the top.