[sdiy] Substitute for pin matrixes?

[John Mahoney]

More half-baked ideas:

Make a 2-sided PCB for the matrix -- rows on one side, columns on the 
other (obviously). At the row/col intersections are circular pads. 
Each circle is divided in half, where one half is the row contact and 
the other is the column contact. You need to bridge the gap with a 
conductor to make a connection at that point.

For contacts, I'm (again) thinking magnets, but this time they need 
to be conductive (at least on one surface). Copper or aluminum tape 
should work, or maybe conductive paint.

Make a sandwich with the PCB on top, a thin sheet of plastic for 
insulation, and a piece of steel. The steel gives the magnets 
something to pull on so the connections are fairly solid.

Or...

Nicolas Collins, in his fun book "Handmade Electronic Music" 
(http://www.nicolascollins.com/handmade.htm) discusses the use of 
computer keyboards. They *are* switch matrices. You could use fishing 
weights to hold down the keys.

John