You really don't need anything as fancy. A small magnet and a narrow aluminum tube will do just fine. It won't be quite as impressive, but drop a pebble from the same height not through the tube and watch the delay for the magnet dropping. A four foot length of tube about 1/2 to 3/4 inch in diameter would do nicely.

Edit: try cast iron if you must have a big pipe. It's likely to be much cheaper. The thickness shouldn't make much of a difference either, so maybe even a cooking pot with a cut off bottom would work.

Would a thinner wall tube work just as well? It seems the effect depends on electrical conduction which should be sufficient even with much less copper. Or does it depend on how many flux lines are hitting the copper cross section?

It also works with a small neodymium magnet which can be bought for less than $1 and a small copper plumbing tube which costs about the same.

I found a kit (magnet + copper tube) here: http://www.teachersource.com/product/645/electricity-magneti...

Not on the same scale, but appears to be designed to demonstrate the same concept.

Not sure where to get one at that thickness or diameter, but a specialized plumbing supply company can get you most standard size and diameter of copper piping.

That one is huge, though. In theory, this should work with smaller, but powerful magnets, and thinner tubes, correct?