I would suggest you try building and using a Wimshurst machine
- It generates sparks (2 or 3 cm spark length easily reached)
- It can light a fluorescent light bulb (just hold nearby while cranking)
- Usually includes capacitors to demonstrate storing energy
- Is not electrically complicated
- Demonstrates generation of static electricity without direct friction
- Is mechanically simpler than a Van de Graff generator.
There are kits and finished machines avaliable, but you can build a Wimshurst machine in your garage workshop from parts you can get from a hardware store. I found I needed a drill press for some of the parts - hand drilled holes aren't straight enough for longer holes.
The difficulties in building Wimshurst machine are mostly mechanical.
You need some kind of bearings for the disks to run on, and you need to cut circles out of a plexiglas sheet. I used some plastic wheels with bearings for my disks to run on because I could get them cheap. One of the links below explains how to cut the disks.
Electrically, you do have to watch for sharp corners on the conductors - the charge "leaks" off through sharp corners, so smooth and sand everything round and use rods for connections as much as possible instead of flat metal.
You would have the same difficulties when building a Van de Graff generator, and more mechanical problems besides - most Van de Graff generators have a large dome for the charge collector, which can be difficult to make. The belt for the charge transport is also a problem.
Electrically, the Van de Graff is even trickier - the voltage can be so much higher that leakage is a much larger problem.
You also have to deal with powering it. While you could build a hand cranked Van de Graff generator, most information is about motor powered ones - probably because they take more cranking to build up a usable charge.
An alternative would be a Kelvin water dropper. It uses falling water drops to generate a static charge. I've never built one, so I don't know how well it would do for lighting things up.
- Link to a guy who built a fairly simple Wimshurst machine with detailed instructions
- Link to a Wimshurst related question here on stackexchange
This is my Wimshurst machine:
As you can see, it is mechanically fairly crude, but it does work.
I'll see about making a picture of it flashing a fluorescent lightbulb and post it later.
For something much simpler:
Scruff across the carpet wearing sneakers while carrying a fluorescent tube. Walk over to a door and touch one end of the tube to the doorknob and watch the tube flash.