Experimenting with tiny objects is hard! I spend so much time on the floor looking for things I have dropped and can’t see them because they are so small!
They have to be so small otherwise I wouldn’t be able to put them under the same pressure.
I am trying to make conditions similar to inside a planet which has loads of pressure on it. The smaller the objected the easier it is to put under this pressure (and the quicker I can heat it up) because it has less mass.
If my experiments were the size of a tennis ball I’d need something the size of a building to get the same conditions. This wouldn’t be practical and it would be REALLY expensive!