Instant video download includes printable prop PDF.
You propose a friendly psychological experiment. Using some 'test cards' your participant dreams up a crazy image in their mind - they never say anything about the image in their mind and there are quite obviously myriad outcomes to the procedure.
Even so, when the 'test card' is pulled apart, the very image they have dreamed up inside their mind is printed inside!
Easy, intriguing mentalism for any occasion!