Mechanical question

[dhouston]

You can easily obtain a metal template from an old pc. Remove the db9 connector and cut a rectangle
Containing both the db9 template plus the two fixing holes.

With most PCB Mount DB-9 connectors, you need a rectangular opening that encompasses the extended nuts for affixing the cable. IOW, the fixing holes are within the needed cut-out so you cannot affix the template this way.