Hi Mr. Ben,
Like everyone else, I really enjoy the show and am a little jealous of what you do 
I have a question for you, I have an idea for a project, althought I ran into a hitch in my design.
Let's say I have a circle with a 1.75" diameter (PCB), within that circle I want to fill 1.5" of that area with sensors/push buttons/touch resisitive area. I;m really not sure what to put in there, but I need it to measure distance between two points within that area.
As well it has to be somewhat acurate, hopefully within a milimeter. So if something is put in within that area it can measure the diameter of that. I hope you can visualize what I'm trying to accomplish.
I was thinking push buttons, but I'm not sure how I would fit enough to get the results I need.
The calculation would be done with an arduino, as that's about the only microcontroller I can program.
Look forward to hearing from you, if you do have an idea or a suggestion.
Pawel.