Rapid-prototyping is a means of "printing" working 3D objects directly from a 3D computer file.
Q-BA-MAZE has an underlying geometric simplicity since it is just a system of cubes. But an endless complexity lies in the details of these cubes -- the internal geometry that slows the cascading balls and the joinery that allows daring cantilevers required months of design investigation.
Rapid-prototyping was at the heart of these investigations. I made at least eight generations of the design in this way. With each iteration, lessons were learned and the design improved for the next round. I usually made about 6 cubes in each generation, enough to test the joinery and the movement of the balls through a simple configuration.
This gray cube is the first generation. The side joinery is a kind of split dove-tail connection that reveals my background in woodworking. This joinery was not rigid enough. The bottom edge of the cube had an unacceptable "accordian" action. 
This red cube is the second generation. The side-joint now has a "hook" shape. The "accordian" on the bottom edge is gone. The interior of the cube is a cylinder in an attempt to make a shape that would keep the balls rolling. The cylinder and the uninterrupted bottom edge also work together to increase the rigidity of the part.
This is the "solid" version. I had noticed that Philippe Starck's Ghost Chair had polycarbonate resin in excess of 1/4". I thought making the walls so thick would be the way to give the design quality through solidity and a beauty similar to crystal glassware. The thickness also allowed the corners of the cube to become rounded and pleasing to the touch. This was a bomb-proof design that proved to be far to expensive to manufacture because of the sheer volume of resin required and the size of the press to run the mold. It also turned out to just seem heavy and clunky rather than luxurious.
In this generation the scale of the cube is reduced from a 2" cube to a 1 1/2" cube in order to make the cubes fit more comfortably in the hand. And four internal ribs are added to give the part strength and solidity through engineering rather than heft.
In this final rapid prototype generation (I've skipped over a couple of generations in which the developments are very subtle), a concave-up sphere now forms the interior geometry of the cube from edge to edge and the side-joint is unified as a "horseshoe" rather than being split in two parts. The round corners of the "solid" version have returned to the design to make the cubes pleasing to the touch, to increase surface area with the interconnecting bottom-pins, and to ease the flow of the hot liquid resin during molding. The four ribs have also been extended upward, in the upper half of the cube, to form "buttresses" or a kind of box-beam in every corner. Satisfied that the design now had the right form, feel, and function, the design was ready for making the production tools for injection molding.
Here is the final molded polycarbonate part -- embodying the lessons of the many generations of rapid-prototypes that came before it.
This is post #2 in a series on "The Making of Q-BA-MAZE"
