The first cars of theirs that I saw built up were a set of their fluted side streamliners, which were built by Jerry White. Currently  in the collection of Ed Morlok, this is the observation car. The streamline car sides and roof were made from one piece of copper with an aluminum round end on the observation.
They produced an extensive line that was available in HO, OO, S, and O gauges. The earliest advertisement I have found is in the April, 1946 issue of Model Railroader. They describe the car sides in their 1946 catalog as being made of "moulded" copper with “infinite detail.” The 1946 catalog lists the following sides:
100 Standard coach
102 PRR coach
104 Club car
202 Staggered window roomette
600 Interurban, heavy, pass-bagg
The standard, heavyweight passenger cars listed above were sold as sides only. To use them you would have to combine their parts with wood parts you supplied (from perhaps a J-C kit). Matching car ends were available from Exacta.
Exacta also produced a complete train of nine (!) fluted side streamline cars, including the round end observation in the photo at the beginning of this article. The full list of these cars is in the image linked above from the HOSeeker site. The page that links to Exacta information on the HOSeeker site is here.
They also advertised several freight cars, none of which I have ever seen. Their advertisement in the September, 1946 issue of Model Railroader features a prototype photo of their all-metal caboose, built to plans supplied by the Magor Car Corp. as “used on so many railroads.” The advertisement continued
PERFECTLY SCALED IN LUSTROUS MOLDED COPPERThe OO version of the caboose sold for $7, and it was also produced in HO, S, and O gauges. Besides this C&O C-10 caboose, they also advertised a 40’ gondola, a mill gondola, and a hopper. Advertising for the caboose from 1947 may be seen in this article.
90% correct detail. Recessed doors and windows. Kit includes sides, top, cupola, ends of molded copper; underframe of aluminum, wood moldings for top.
Personally, I think the "90%" correct detail mentioned prominently in their advertising was a bit of a blunder, who wants a car that is 90% correct? What they wanted to communicate was the rivet detail was 90% correct, as opposed to other makers where the rivets were more representational than correct. In any event, these don't look like they would be easy to build at all and I strongly suspect more of their products were shipped out in gauges other than OO. Exacta is rare in any scale, and these are certainly cars to keep your eyes peeled for.
I should also note, if you have a smooth side OO streamliner with aluminum sides, it is an example of the Zuhr streamliner. More info here.
The detail incorporated in these electroplated car sides is abundant and has eye appeal. Considerable third dimension is obtained with the process, and the copper sides and ends can be soldered together without difficulty. Windows and door openings are outlined but are not supplied punched out. Detailed plans and instructions are included.Later advertising mentions that the windows are punched out, which would be something modelers would very much want to have done at the factory.
By June of 1947 they advertised only HO and O models. Of the extensive list above how much was actually produced is a good question. All I know that was produced for sure is their Budd streamliner seen in the photo at the beginning of this article. But see next UPDATE!
UPDATE 2015: Yes, I now have a set of the #201 Pullman sides/ends! They were produced and are nicely made, see this article for more.
UPDATE 2016: And note the link and photo of cars built with almost certainly their baggage car sides.
For more see: