I start this project because I wanted a way to build these structures beyond the size capabilities of most 3D printers. It's also substantially cheaper to substitue dowels, which cost about $0.02 per cubic inch, instead of printing the straight sections.
All the dimensions given are specific to the form I built, any of them can be altered to fit your needs.
Step 1: Wireframe
Build a wireframe. I built mine from an analysis of the motion of drinking coffee. I will elaborate on this process either in a later Intractable or as addition to this one.