Parametric Xmas-Tree top is a simple, but effective example how to force 3D software to do modelling for you. User creates a basic 2D profile and then a Marionette network recreates it into 3D shape consisting of twisted NURBS extrusions. Number of extrusions is controlled by the User. 

.stl file has 5 variations, printing time for each is around 4-5 hours

To run a Marionette network you need to have the Vectorworks software. To download a .vwx file visit: https://forum.vectorworks.net/index.php?/files/file/314-xmas-tree-top-generator/