I have a thing for 'lenses'. Grinding tiny dimples into the edges of of a thick magnifying glass let me close a pair of calipers on it, to hold it securely, but thinly... I'm not exactly sure how they make hourglasses, but I bought this one years ago... I positioned the lens in front of the center of the h.g., in front of my computer screen (one which I just got rid of...) Replace the black background shown with that, line things up, and you have the picture.
