That kid should have some monster forearms to be able to wrist flick plutonium and beryllium. His grip strength would crush your arm like an overripe banana. Plutonium is almost twice as dense as lead (though beryllium is almost 10 times less dense than lead).
There are 3d models of the demon core, so one would make a plastic version of this game. It'd be missing the cool blue flash you get from winning, but its good to test these kinds of things before you dig into your plutonium stockpile.
Fixed how? The only two posts from here that I've seen in a long while were this one and an anti-scientific method wojak meme trying to make a statement about capitalism.