Engine Cowling
The turbine blades look out of place without a nice rounded cowl to guide the fluid into them. I extracted the cowl from the same jet engine (so I know it is scaled appropriately), and split it into 120 degree sections so that all 3 parts would fit on the bed together. This print was left to run overnight and I learned a lot about support materials. Nearly 5 hours into the print the machine had only printed a little lip from under the cowl and 75% support material to print the cowl on. I totally should have reduced that lip to a few mm (just the bare minimum to fit into the next piece) and it would have spent far less time printing bits to be thrown away. (stl here)