Delta Smart Effector Circular Fan Duct

Quick Start
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This Thing is a circular or semi-circular fan duct for use with the Duet3D
Delta Smart Effector. It consists of two parts:

* EffectorCircularFanDuct -- This is the fan duct itself. I provide three
variant STL files, for 180, 270, and 360 degrees of surround.
* EffectorFanBracket -- This is a (very slightly) modified version of the
bracket that attaches the fan to the Duet3D Delta Smart Effector.

I provide both OpenSCAD (.scad) and STL files for both part