That is non-sequitur.
An object being physical and countable has nothing to do with how many of them might exist, possibly an infinite number of protons throughout the infinite space (and is even probable).
Of course there is. If you can count the balls outside of the container, then you know that you can count the balls inside of the container. The balls outside of the container just demonstrate countability. In order to prove my point, I just had to prove that balls are, in fact, countable to begin with, but I can’t point you to a ball (I guess I could post a picture of a ball, but technically, that is not a ball in and of itself) and say, “One,” then another and say, “Two.”
Let me know when you can count protons with your naked eye.
goddamnit i made a post that didn’t fucking POSTTTT
i basically said ur still omitting premises from your argument, which is very convenient for you and inconvenient for me. bad arguments rest on unexamined premises.
Call me uncreative, but I stopped reading right there.
If I was to be contained, I think a container with infinite capacity would be the way to go. 
I can see your point!
Premise 1: There is a container.
Premise 2: We are putting balls into the container.
Premise 3: The balls must come from outside of the container.
If we can count balls that are outside of the container, and the balls that are inside of the container came from outside of the container (at some point), then we can also count the balls that are inside of the container. If we can count the balls inside of the container, the result cannot be infinity because infinity is uncountable.
If you grant that we can have an infinite number of balls piled outside the container, we can reach into the pile and take three balls from that pile. It doesn’t make the number of balls in the pile any less infinite, and we have a countable group (the three in our hand) and an uncountable group (the infinite pile). We can put the three in a container and have a countable number in there and an infinite number outside. We can put the pile inside and have an infinite number inside and a countable number outside.
Practical considerations aside, of course.
Here is my understanding:
Firstly, in 3-dimensions, a container of infinite size is a non-sequitur. There could be no ‘outside’ to such a container.
But granting the premise, according to Cantor such a container has a qualitatively different level of infinity (alph1) to the infinite number of balls (alph0) and is greater.
The number of balls is a countable infinity, whereas the space inside the (impossible) container is not.
How are you able to put the pile in there without theoretically being able to count the pile? I grant you that putting the pile in there all at once would make it difficult to count, but who says you have to?
balls are already countable, it doesn’t matter where they come from. you can count balls. this convoluted logic is totally unnecessary – and still making some weird assumptions that you didn’t make clear but that I can infer.
I wonder if I should mention that this is just an IQ test… 
Just playing along…
How many infinitesimal balls can be in a one inch cube?
Cantor had issues. Again, it is just a question of divisibility. Why does an empty space have any more parts (divisible regions) than the number of infinitesimal balls that could be assigned to those regions?
I’d first have to know what you mean by an “infinitesimal ball”.