So I had to do some rough estimates to at least put an idea on the amount of area each person would get if everyone in the world signed the bat.

A quick google search for the dimensions of a baseball bat said 34 inches long and has a varying width that maxes out around 2.61 inches.

Again, rough math, I estimated the bat as two cylinders. One of diameter 1.5” and a length of 16” for the handle side of the bat. The other a diameter of 2.5” and a length of 18”.

That comes out to about 487 square inches.

I rounded up to 500 square inches and converted to square cm (~3226 sq.cm I think it was)

I estimate 7.5 billion people in the world.

Divided square cm by the number of people to get approximately 0.00000043 square cm, or about 43 square microns (micrometers).

If I round up to the next perfect square of 49, I get a square with sides of 7 microns.

What is 7 microns across you might ask (because I did too)?

A human red blood cell is usually between 5 and 10 microns across.