Its the base to some scales. 

You are on the Australian forums. Try asking on the US forums in case this item is something specific to the US. 

My first thought would be some vintage scales too, but I am not sure how it worked. There are similar vintage scales with weights at the front, but those in your photo are trays, and they seem to be all connected (and also connected to the device). Maybe they put some weights on them?

Miniature Mini Balance Scale Cast Iron Set Salesman's Sample or Toy