The official things were giving a 404, so I made it myself. Enjoy!
PTC provided a 3d field model in CAD, and I was going to post a step file, but I don’t know how to put it in my post. Here’s the url to the PTC downloads of the field and parts.
If you are looking for a STEP file of the FRC 2012 Competition Field, refer to the Autodesk Education Community. I have posted an Autodesk Inventor 2012 version and a STEP version.