For ‘54 the motto for Buick was “The Beautiful Buy.”

@john-quilter John, thank-you for taking trouble to post this information.  It is fascinating and your craftsmanship very impressive.  I am intrigued by your station wagon extension which makes for a handsome finished model.  Would I be right in thinking this is sheet aluminium we see in your pictures. And there is a grey resin / filler we see at the intersection of original and new parts: might I ask what product this is? Or is that a trade secret?

On the Chrysler station wagon the roof extension, tailgate, and rear quarters are in fact sheet aluminum,  easily available at hardware stores. My joining and shaping compound is J B Weld which can also be used as a glue.  Some times Gorilla super glue gel is used some times for attaching small parts white glue like Elmers and even sometimes two part epoxy.   No secrets here, I encourage folks to do some custom creations of their own.  Google images provides great photographs to work with.   Shapes, color choices, interior details etc.

@john-quilter My thanks again. I in fact used Araldite as a resin to re-mould the shattered wing of a Bugatti Royale but did this of my own intuition and hence my asking after the professional way of doing things. I did find the Araldite sanded-down to a nice surface, but for future experimentation, I'm going to invest in your J B Weld.  Again, it is inspirational to see your nicely finished re-workings.