Does anyone have the cad files for the 4inch omni's
If you go to the product page on vexrobotics.com , for example here: https://www.vexrobotics.com/edr-wheels.html#CAD_Files You'll find the download of the current CAD for parts. Import the .step file into your CAD program and save it in the format appropriate for your particular software.
If you're running Solidworks, there is a solidworks format file in this library: http://www.mediafire.com/download/3v7rf1xkqs7kh75/Team_7479_Solidworks_Library.zip
For Autodesk software, someone else will have to chime it, as I only use Solidworks.