I did this as a kid - serious fun. Used the americium from a smoke detector as a source, after several abortive attempts to build a synchrotron... The third tim

I did this as a kid - serious fun. Used the americium from a smoke detector as a source, after several abortive attempts to build a synchrotron... The third time you wind several km of copper just to end up melting it is the last time, it turns out - particularly after you explain to your parents what exactly it is you're trying to do. Either way, a small radioactive source is just great for some neat photos and the occasional decay trace. Leftovers from my melty mess went into a tesla coil, so not all was lost.