Geeetech A10 (Late 2018) Part Cooling Duct

Model originally uploaded to Thingiverse at https://www.thingiverse.com/thing:4691067.

I had a lot of trouble finding a fan duct model which worked on the late 2018 version of the Geeetech A10 - all the versions I found were too wide and didn't work. This is a reimplementation that's close to the original, with some modifications for easier printing.