This is a 90 degree elbow for 2.5 inch vacuum systems found in the USA. It can be scaled to fit other standards.
Update: version 2 added. I noticed that the male end was a little too small and the female end a little too large. (story of my life...) I adjusted each by 0.5 mm. If only life were that simple...
0.6 mm wide x 0.3 mm thick
Use PETG or some other tough filament. Print strong because there will be a good deal of stress on the elbow.