For close/parlour the kalver detector he revealed in a magi mag is excellent.it requires a fart machine.THE FIRST ONES MADE not the #II version.they can be had on ebay for less than $10.add the adjusting knob but resist the temptation to add lites.don't use decals stating"lie detector"this tells that it is phony.they must believe that the thing is real up until the end when you give it away by a comic response.