Doesn't even need to be metal: they make sure you aren't touching skin-to-skin anywhere while you are in the machine (for example, don't put your hands together) in order to avoid induced current loop burns.
I like the idea but there were several examples where I found a word but it was not the word the game wanted, and I was told "invalid word". Examples: I found "STONE" but the correct word was "NOTES", or "SPILL" vs "PILLS" etc. Extremely frustrating!
https://riteadvantage.com/understanding-and-reducing-burns-i...