Ever make a circuit board? I used to do it in high school. It was not much fun really. First you had to coat the boards with a special coating that was sensitive to UV light. Then you had to make a transparency mask of your board. You then exposed the board to transfer the circuit diagram to the board. Now comes the nasty part. You put the board into an acid bath to etch the board, removing the copper where you did not need it. Dealing with the etchant was very messy.
One would expect the ball to melt it’s way through.
It doesn’t because floral foam is a foamed thermoset plastic which burns rather melting. Had the foam been styrene or another thermoplastic foam the block would have melted. But enough of that TMI crap, just watch the video.