Looking into building a spectrophotometer. Damn pricy to buy on ebay, but I reckon I should be able to knock one up for very little, just need to get a decent high-resolution webcam, open it up, cut out the IR filter, and use a DVD for a diffraction grating. And get myself some wideband light sources in the UV and near-IR ranges to play around with.
A cyclotron might be fun sometime too, for a future project. Always thought it would be neat as hell to have my own bench-top particle accelerator. Although achieving the hard vacuum states needed looks difficult, and all the copper for wiring beam confinement magnets, lead for shielding would prove expensive.
