I took MNinventers nice Train design that was published Dec 26, 2011 and splitted it into parts for printing without support using Sketchup Make. All fixed with netfabb cloud service and test printed. I also wanted the wheels to be able to turn, making it a toy.
Print the pieces from the colors and in amount that is given in the file names and glue them together in the end. I didn't use any support at all. I printed the main top part three times to get it perfect and ended up combining back roof and the tiny parts on it.
There are two variants of the design. The first uses the main top body with roof. So only print 00 piece for that and skip parts 01 - 04. I used 0.08 mm layers to make the surface smooth, 20% infill and 2 loops should be enough.
For the second one I removed the roof and the tiny parts on it. Print parts 01 - 04 for it.
Then print parts 05 - 17 for both variants. Print at least the 08 axis with 40-60% infill to make them enough stable not to break.
You can print the blank plates piece 18 and combine them with your own words or signs. I printed them black letters/numbers on red plates using the Print on Object plugin in Cura.