Some "N" scalers (model railroad enthusiasts) had their cute little trains on display at my local library.  These trains are 1/160 actual size, and the track rails are only 9 mm apart.  They look bigger in this cha-cha as my stereo base was only about 2 cm (less than an inch).  Depth of field was shallow as in all macro shots, but I cheated a little by focusing the first shot on the front of the engine, and the other on the middle of the car behind it.  When f used in 3D it gives the illusion of more DOF than there actually is. 

 

Duke