Would you be willing to upload to thingverse?I've made a 3D model of NATi's itx kit and uploaded .STEP files that you can use for your prototype.
The model may differ with +/- 0.5mm but should be quite accurate. Link to download:
.STEP - ITX kit v1.337 rev2 by NATi
Send me a mail if you find any problem or have questions: email@example.com