Railguns are fun to build as a hobby project. All you need are a pair of rails, and a conductive slug. Ball bearings work well. The tricky bit is reducing arci

Railguns are fun to build as a hobby project. All you need are a pair of rails, and a conductive slug. Ball bearings work well. The tricky bit is reducing arcing between the rails and the slug, as you can end up with it either welding onto the rails, or carbonising and ending up with "dead patches", sapping your power. Main trick was to go for gobs of current with as low a voltage as we could manage. We used big capacitors re-purposed from a tesla coil (cider jars!), and copper plumbing pipe filled with gravity-fed circulating mineral oil to keep the temperature manageable. Think it was 1.5m long or so, and we were using a 10mm ball bearing... and it happily disappeared deep into a brick wall never to be seen again. Fun times, but lethal if you're not careful.