Iron Ball Jar Mold (bicentennial)

This is an (iron?) mold for a Bicentennial Ball jar.

The dimensions for the jar it would make are approximately:

5.5” tall (it looks like the mold is just to the neck of the jar)
2.75” mouth
3.75” diameter

On one side the jar would say Ball with the little ® under the word. Below the Ball is IDEAL and lower A14

The other side is an eagle with the words * Bicentennial Celebration * and 1776 * 1976 around the eagle. and MADE IN U.S.A.

The base has 5 rings each around and bigger than the next with A14 and 752

The mold is in 3 pieces and it looks like at least one more piece would be bolted to the top of the 2 side pieces.

It is very heavy. I would guess at least 40lbs.

I just wondering about the items rarity and any history associated with it.

Thanks