Make a box that has two electrodes that the person puts their thumbs on and that controls the current going to a comparator and a buzzer. Call it a "homeopathic truth detector". It will give about as reliable results as the "real" thing.It seems like everything has already been done. And abstraction all seems to be FREE of charge on the Internet. Be nice to sell them in real life in my very own electronics retail shop for AUD $7.50 ea...