3d model for Urethane casting, single piece 90mmx120mmx5mm

I have a pcb 80mm x 110mm and I'd like a case proototyped. I've looked at facfox & want to prototype the bottom of the case in abs style casting.

There are some pictures of the pcb on colddevices.com, the 3d model for the lower part obviously has holes for the screws and some kind of lip to mate with the top of the case (I will not make the top of the case yet, i want to see how the bottom looks first.

so it's a simple model, but need support also to get the file loaded into facfox. let me know if any questions..