The setup is simple really: All I use is an old transparent CD storage box, some water and my trusty old A4 lightbox for lighting. For the bottom of the box I have a piece of gray Lego baseplate cut in form and hotglued on a piece of acrylic sheet to give it some weight. Legos float because of all the air trapped inside individual pieces.
I had a wacky idea to submerge everything in water, it slows down everything that moves. The water also causes light to reflect from solid surfaces in a way that sometimes helps hiding the miniature scale.
Source: flickr
