Step 1: The Circuit
The circuit uses three NPN transistors to detect a static charge, and turn on or off an LED accordingly. I used a 1M ohm potentiometer as a sensitivity adjustment knob.
Step 2: The Case
I 3d printed the case; the file can be found at http://www.thingiverse.com/thing:823499 . I also included an on/off switch(not in the schematic) the circuit runs on 6 volts, so I made a compartment for two 3v batteries using two plates salvaged from an old battery holder. They fit into a depression in the 3d printed case and can be soldered to the circuit.