I should have looked at the link to the pen holder that you had on the original post and I would have noticed that you were looking for a model type double sided carve. Perhaps someone will convert them for you if you supply a link to the models you found online.
Lawrence, The model was found on the internet in 3DS format. There was problems with it as seen in the first I uploaded. Mostly too many vertexes not attached and and open area on the bottom. The second attempt I went into the model and closed the open areas, attached the canopy to the plane, and repaired the holes. Problem was in cutting the model since the wings slant down, and trying to get a good cut on the top including the whole wing. Plus anyone that carves it will have to do some hand work on the split back wings. CW will not do carving under those wings.
The software I used to edit it was Silo ($99.00), and meshlab (free)to make the STL file. There are all sorts of free 3d models on the internet.
Using Designer 1.187, STL importer, Center line, conforming vectors, scanning probe/PE, and the ROCK chuck.