I built this mockup for my roomate in 1991. He wanted a working prop for the MIT 10K Entrepeneur's competition. His entry was for improved interfaces between PCs and CNC machine tools.

For the contest, this trackball was used to run the demo software. The concept was a CNC operator able to move freely around the machine for example to jog the axes during a setup.

I almost forgot- they won and founded Mule Automation which was bought by Boston Digital.