I need to edit a car to test spoilers, I want to keep this short. I am using sketchup to edit the car.
Screenshot (19).jpg This was a curved surface so I opened it and need to connect it to make it a flat surface, unfortunalty when it does register as a face even when I click on the edges or use the make face plugin, if you want to help me edit it, email me at GenZod23@gmail.com because the file is too big to post here.

But the other problem is that it is hollow from the inside, Im using a Makerbot Replicator 2 and I used makerware to test a hollow cube and a filled in cube of the same size and it said it would take the same amount of filiament, so does that mean I need to make a cupholder kind of thing on the car?

Thanks and please respond, this is a time sensitive issue...I kinda screwed up trying to hard.