Electroplating process using chromium uses hazardous chemicals. Vacuum metalizing is fairly safe. This process uses aluminum as the metal which produces the chrome-like finish
See the attached link for some basic info, or Google for "vacuum metalizing process".

But some kit companies (like Trumpeter) have used actual electroplating process for their kit's chrome finish. That results in a thicker layer of metal over the plastic which makes difficult to expose bare plastic on glued surfaces or to strip the metal to repaint them.