D&D 5E What to do with ball bearings?

[seebs]

Now, now, let's just keep the thread moving, we don't need any friction.

 

[aramis erak]

One other use came to mind: slope detection. a ball bearing rolls downhill at a speed determined by the slope. It's quite possible to use them for civil engineering purposes that way.

 

[Hand of Evil]

I am sure there is a race out there that sees them as trade items...War-Forged...and I hear tell that some mechanical monsters see them as catnip!