Making A Surface Error

I opened this model that I got from Hondas 3d Cars Archive because I need to put holes in back so I can put attachable spoilers after I print it.

Unfortunaltly when I try to make faces, it does not connect back, it was curved before, now I took it apart to make it flat, but it wont read as a face. I clicked on the edges and everything, it wont work, I even used the make face plugin, it wont work either.
Can someone please help me, this is a very big grade in my science class.
Thanks, and if you want to see it for yourself email me at because this file it to big to put up here. Thanks

Or you can upload to file sharing site like drop box or Google drive

Google “Honda 3d car archive”

The models are very high resolution .stl files. The high poly model has 2 million faces, the low poly has 200,000 faces. The meshes are very organic. Here’s one model in Meshlab - this is the low poly version.

Does attaching spoiler after printing mean you are trying to 3 d print the model and do you have access to a 3d printer? To have it printed by a commercial company will be expensive unless you can make it a shell because cost depends on the amount of material they have to use. It also needs to be a solid aka water tight model.

No need to e mail model got what I guess it is from Honda link.
There is a plugin called tools on surface by Fredo that may help you cut holes on a face. The one model I guess you are using I opened in Netfabb ( free version) and it reports closed and orientable. Netfab has free cloud service where they will check and repair model if possible… The other problem may be mirrors and getting support for them.
One other suggestion jnstead of your approach select the face where you want the hole and make it a component, make copy off to side, select that copy so you are in its edit context and extrude the hole. That same hole will now appear in all the same componets. Close the edit context and delete the copy and the hole will now be added to the model.
Note Shapeways provides info on the design on swappable joints’
The attached file is from the Honda site ( nsx) concept, I then use a program to decimate the number of edges, use the concept above to extrude hole in back lid
Dropbox - Error.
This link is a skp file that is solid: Dropbox - Error. The SU model being solid is only a necessary but not sufficient condition it is printable. Some of the commercial printers have there own checks and they will not print if it does not meet their criteria.