Great fun Soup, and as you rightly said, because we are looking at a 2D image, it has the effect of making it look like a protruding rather than receding image.
I can't tell you the details of exactly how to do this next bit as the dimensions and angles are all vital but taking a plaster cast of the sort you did in flour, , if you build a set of mirrors where you put two together at 90 degrees and the receding image underneath and angled so it shows in the two mirrors, you will get an amazing effect: it will look like a floating 3d version of the face in front ot the mirrors. This is because you will see one image of the face as a regression and the other one as a protrusion perfectly positioned so that the two are combined. You feel like you can reach in and pick up the image even though it isn't actually there!
Now that is not something I can reproduce for you on here for obvious reasons but if you ever go to the Science Museum in London, you will see a couple of these and the effect is quite startling.
Right, i'm gonna shut up now as I have probably confused everyone big time. Where's my coat?
Cheers,
Rob
