There were at most 2 prototype fiberglass Kiss cabinets made. Until the fall Expo I thought only one existed, and assumed destroyed, until I was shown the sample from Germany.

These should not be confused with the blue VF display 'New Technology' Kiss prototype games, of which 11 were made and many are still in the hands of collectors. Working on an IPDB entry for these games to be published soon.

The fiberglass cabinet indeed proved too fragile for this use. On top of that it was too light and the game did not have the physical feel of a pinball. When displayed at the show weight was added in the form of sandbags so the game would at least 'feel' right.
As for the playfield composite material. We tried that on a number of games in small protype batches. While the material proved viable as an alternative in anticipation of a future lumber shortage, it was difficult to paint properly and more expensive than plywood. When shortages did not materialize the project was mothballed.