This article describes the construction of a 3D Printed Clothes Hanger:

When not in use, the hanger folds (almost) flat:
Each hanger requires 6 3D Printed Parts (STL Files Here)

You will need to print 4 Arms and 2 Plates. I use 0.2mm layer height, 20% infill and “High Quality” print settings:

Drill out the screw holes with a 3mm drill. then thread 4 key rings on each arm:

Followed by 4 clips:

You will need 8 x M3 x 12mm countersunk screws and 8 x M3 Nuts:

If you look carefully at the plate, the two corners with square edges are used for the fixed arms, the two corners with the rounded edges the movable arms. Fix the two fixed arms to the top plate with a M3 nut underneath – this is recessed into the underside of the arm:

Leave the bottom plate off for now:

Then fix the two movable arms, then the bottom plate. Don’t tighten these screws too much otherwise you won’t be able to open the arms!
Screw a small eye screw in the centre hole of the top plate.

Thread a lightweight carabiner through the eye to hang it on a hook or washing line:

All done!

Part sources:

• Key Rings: “25mm Nickel Steel Split Keyrings” (Ebay)
• Pegs: “Stainless Steel Washing Line Clothes Pegs” (Ebay)
• Carabiner:  “D Shape Carabiner” (Ebay)