I have been meaning to do this with some 1/18 BBI stuff. It is a matter of depth of field. You want to use a low f-stop to blur out the background and then mess around with the distance away from your 12" figure (like a 1/18 humvee ). It really helps to have a SLR or DSLR camera and a macro lense make this even easier.
I haven't used different sized figures and made them look the same size but I have used figures that where the same size and made them look different sizes. Snake and the Metal Gear in the photo are the same size (which I suppose makes them different scales).
A forum community dedicated to One-Sixth scale action figure owners and enthusiasts. Come join the discussion about collections, kitbashs, customizations, displays, models, styles, scales, reviews, accessories, classifieds, and more!