Here are my KiCad templates for PCI Express add-in cards. They are standard sizes based on "PCI EXPRESS CARD ELECTROMECHANICAL SPECIFICATION, REV. 2.0" document
In order to use those templates you will need my symbol and footprint libraries for PCIe
These templates are distributed in the hope that they will be useful, but WITHOUT ANY WARRANTY
DXF files available for you to create your own board shapes.
All files availaible under Creative Commons attribution. cc-by dbozec