Back in the early 1980's, when my children were small, I made a bunch of wood toy models including John Deere tractors and sileage wagons. In April 2011, my Mother returned 1 set to me from her house. It has been well used by many grandkids, but only damage was broken smokestack:
I drew up the pattern for making this tractor set in Google Sketchup. I also made a traditional grain wagon design also:
Now that I have the design recorded in Sketchup, I can make some more models in the future.