Physics project ideas beyond potato guns and dry ice

[Viper2838]

I was wondering if anyone could aid me in finding an idea for a new project. I was quite sure where to place this thread, so forgiveme if its in the wrong place.
School has just started, and as usual, I am stuck with loads of free time until my classes get up to speed. I figured I would be able to put this time to some good use.
I have done the usual potato guns, and dry ice bombs, and I am looking for something a little more challangeing. It would be nice if your ideas would be a tad bit less likely to get me arrested then my previous endevors.
Thanks.

 

[Antiphon]

How about making a 10-foot tall Tesla coil?

If you do it correctly, it will launch 10-foot long sparks or longer.

 

[Pythagorean]

build a mini-fusion chamber!

http://www.livejournal.com/community/ubergeeks/276039.html

 

[Geoff St. Germaine]

Build a spherical tokamak. That's what I'm doing.

 

[neurocomp2003]

high school? learn to code your own physics engine...particle systems, rigid bodies, deformation materials, EB stuff...etc.
using real physics and not psuedo modelling.

 

[Viper2838]

high school? learn to code your own physics engine...particle systems, rigid bodies, deformation materials, EB stuff...etc.
using real physics and not psuedo modelling.

I have tried the programing scene, but I have had a hard time teaching myself a ligitamate language.
Yes, I am a high school senior, so I don't have a large budget, which is part of the problem. And my school decided a few years back to end shop class, so I only have limited access to machinery.
How hard would it be to build some thing like a minature linear accelerator?