Does anybody know this movie. I'm starting to think I imagined it. Help?

[deadwing]

In the late 70's, early 80's, I remember seeing something on the telly. My dad didn't have a VHS then so it was on the tv. I'm not sure if it was a movie, tv movie or an episode of something like Twilight Zone.

All I remember is it was in a young woman's house. In the center of one room, there was a very large metal/steel cube. One guy falls into this cube and while he's inside, it starts to twist and change shape. Squashing him inside.The man is screaming and blood starts to pour out. All this while the woman is watching.
This is all I remember. It's been bugging me for years and I just want to see this again. Anybody got any ideas.