Imagine a model train set, with a model building of a model train hobbyist at work — on a working model model-train set in that little model building. David Smith created a 1:35,200-scale train set (no wider in total width of the set, than your pinky fingernail).
The preview screen shows how small it is, by holding a ball-point pen next to it. It cost about 6 British Pounds (or USD $9.84) to make, and is fully working, with a little car that makes a journey around an elliptical track complete with mountain pass and painted backdrop.
This detailed photo gallery shows a few steps of the process the hobbyist went through to create the eensy set.