Grandson on 8th birthday opening my present to him

I made my grandson work for his birthday present. I supplied tools: scissors, pliers with wire cutters, screwdriver and a hammer. First he had to cut the cords tied around a cardboard box. (No fancy wrapping - just an old box I wrote all over) He opened the box to find this contraption. He cut the tape with the scissors and then used the pliers to cut through the wires. Next he had to use the screwdriver to remove the metal bands. I had placed the wrong bit in the screwdriver to give him something else to puzzle over. At last he was down to the plaster of Paris block. We took it and the hammer outside where he proceeded to smash the block into tiny pieces. Then he had to remove plastic wrap from a cardboard tube and remove the plastic-wrapped present which was a roll of loonies - one dollar coins. I'm not sure what he thinks of his grandpa now. He probably thinks I'm a bit strange. We had fun.