How to "imprint" pattern onto the other side of a face

[neostyles]

Hey all, still using wings3d for things occasionally. Anyway, i modelled a stained glass window except that i accidently did it on one side of the face (didnt mirror the surfaces as i was modellling)

http://i61.tinypic.com/301ki0o.jpg

How would i fix this?

Thanks!

[Nova]

Take the object and duplicate it, then flip it along one of the axes, select the two back faces and bridge them.