dah da-da-daaaaa! 100th post.
Invention time again. Though I think a better phrase might be innovation. On my list of things to do before I die (alongside of 'make a necklace from a bullet that I have been shot with' and 'fire someone'), is 'Make a gauss or rail gun'. I'm sure that a lot of you haven't heard of either, and others will know it only from Half-Life games. Here's a quick layman's description, written by a layman.
A rail gun uses the magnetic force (called the Lorentz force), produced when a conductive object moves simultaneously along 2 rails. One of these rails is positively charged, the other negatively.
A gauss (or coil) gun uses one or more coils of wire around the barrel of a gun to attract the metal projectile towards and through it. These are often set up in sequence to produce a series of accelerating events.
I've seen the "ball bearing" gauss gun (http://www.youtube.com/watch?v=epf1AUvG32M), but I don't count this as a great life achievement to make one myself.
There's also a rail gun experiment (http://scitoys.com/scitoys/scitoys/electro/railgun/railgun.html), but this really isn't very "gun" like.
Instead I will try using a mixture of ring and cylinder magnets. Hopefully I can get the cylinder magnet to accelerate along a "run" of magnets
For a irritatingly narrated look at what rail guns can do, see here: http://www.youtube.com/watch?v=4OqlTXwLG40
Parts for my gun will arrive next week. Time will tell. Sooner or later... time will tell