This thing is intended to evacuate air from plastic bags by blowing trough the orifice. Using the venturi principle the suction generated on the conical inlet does the job. The effectivity is approximately 4:1. This means 4 liters of air blown through the nozzle evacuates 1 liter of air in the bag.
The thing comes in two parts. After printing and cleaning, the two parts need to be glued together.
Join the two parts
To get a functional bag evacuator, you need to glue the wo parts together. Fo me super glue (cyanacrylate) worked quite well.