Step 1: Modeling in AutoCAD
I modeled the shelves in AutoCAD by drawing the shapes in 2D, extruding them into 3D and subtracting the inner volumes. The final shelves will be made from 3/4" plywood, with each unit piece measuring 9" inner diameter and 10.5" outer diameter. The depth of the shelves will be 15". For now I've only built a prototype set which has been scaled down by 1/3 and cut from 1/4" plywood. I exported these shapes from AutoCAD as a single stl file to send to 123D Make.
I've attached the dwg and stl files for both the full sized and scaled versions of my tetris shelves.