We have Open Day coming up and I was considering using the bed of nails. It’s certainly impressive, but I think we may not have enough room or time on the day.
It’s pretty cool though. And the nice thing about it is that the more nails you have on it per unit area, the more dangerous it looks but the safer it actually is (from Pressure = Force / Area).
Then all you need to add is another bed on top, and on top of this a cavity block.
Then smash the block with a sledge-hammer (this to demonstrate the property of inertia).
Then add more beds!