I don't know the intended purpose. And didn't know Gottlieb dabbled in steel cabinets.

I actually worked on a Williams EM one time. It was for a local Lady operator. She had a few games in her garage she wanted me to service. One was a single player Williams in a solid metal cabinet. I think it might have been a Liberty Bell or something from that era.

When I asked her about the cabinet, she said it was made for the military to go on ships since everything had to he "made of metal".

Regardless, I ended up buying a really clean Nip It from her which was sitting under the other three pins.