125mm mechanical ventilation duct adapter for building a fume extractor for 3D printers

This part helps building an extractor hood to handle 3D printer fumes.
It enables attaching an exhaust duct used for home mechanical ventilation and a computer fan.
It was designed to fit with a 120mm standard PC computer fan and a 125mm diameter exhaust duct.
The fan and the adapter can be placed on both side of a quick & dirty cardboard hood and attached with nuts and bolts.