A spacer behind Velocity Stack and Fan Guard for 40mm Fan (round) by admodesi.
http://www.thingiverse.com/thing:2211780
The spacer mounts behind the V stack to provide mounting for a borescope camera.
Created in FreeCAD.
Ender 3 v2, Generic PLA, 0.4mm nozzle, 0.2mm Layer height.
The author hasn't provided the model origin yet.