Inspired by http://www.thingiverse.com/thing:43035, thank you for the idea! :-)

My brother in law is a farmer, his daughters (11 and 14) wanted to test my 3DPrinter... so we ended up designing this tractor on Sketchup (it was a cool lesson, as they learn Sketchup at school), then generating .stl files with Meshlab, slicing with Cura (12.08) and finally we printed wheels and body in white, spacers and nuts in gold. Nuts thread was made on a heated threaded (M4) screw. The wheel is held in place with a tiny nail, the exhaust pipe is a piece of toothpick, the axles are M4 threaded rods.Their Dad enjoyed the gift :-)