My wife has a number of fine gold chains that invariably tangle if stored in a jewellery box, and she's has been asking me for a solution... so here i...t is.
Designed in OpenSCAD, so the design can be varied to suit the materials you have to hand. For example, I had a length of 25mm diameter aluminium tube so I used that (the attached STL files are for that diameter). I didn't try to print the main shaft, as it is easier and neater to use tubing. You can easily vary the number of arms to suit your needs - I recommend 6 or 8.
Uncomment each piece in the source file and generate the STL file before moving on to the next.
Note: The test collar was used to ensure that the shaftDiam variable in the OpenSCAD file is set to the correct value for a nice fit, before starting on the big pieces.
UPDATE: After publishing this item I realised that there was an error in the OpenSCAD code - I had selected 6 arms but, if you look at the photograph, you will see 7! Now corrected...