My inspiration is based on the FTIR display being home built by many people http://www.nuigroup.com/, turns out it is already being prototyped http://www.technologyreview.com/computing/22358/

• Top layer Ultra-High Molecular Weight Polyethylene (UHMW) (or similar working surface material).
• Parallel wire grid with 1 cm spacing, maybe more/less - must test for acceptable resolution.
• Conductive Foam (recycled electronics packaging cpu's/microcontrollers/motherboards etc.) http://www.all-spec.com/products/741-2436.html?utm_source=googlebase&utm_medium=feed. See also http://www.instructables.com/id/DIY-Force-Sensitive-Resistor-FSR/
• Parallel wire grid (orthogonal to top grid).
• USB ⇐⇒ microcontroller ⇐⇒ ADC (or some variation thereof).
• microcontroller code to process sensor into control signals for pad driver.
• pad driver to make use of the pad (based off this work??? http://www.nuigroup.com/).