Can be plugged between hose adn accessories

Is designed to rotate 360°
Held together by 1.75mm fillament

According to Einhell 36mm Hose. 
Hose fittings measure 35-35.5mm (conical friction fit)

Print instructions:

0.2mm leigher height
Maybe prefer PLA over PETG as the hardness might be beneficial minimal friction rotation
Both pieces have a preferred printing direction (part facing the vacuum onto the print bed), no support needed.

Assembly instructions:

1. Ensure the bottom (the end facing the back piece) does not have an elephant foot or it will cause friction when rotating. If it has -> cut/sand that bit off

2. clean up the filament insert hole at the bottom piece

3. Pre-shape/bend a piece of filament for interlocking in a circle. Measure it and cut to length. 
   Having 5-10mm space between the ends where the window in the base is might help reducing friction.

4. Insert front into back piece

5. push in pre-formed filament piece
   

If you do not pre-form the filament for locking the two pieces together, the ends of the filament piece will be straight and cause friction when rotating.