The ability to design the structure of particles at the nanoscale is a key requirement to making this technology work for us in practical ways. In the latest ACS nano, Yang et al. have reported a way of creating gold nanorods tipped with silver. The method involves preparing Au@Ag core-shell rods and then selectively etching away the silver in the middle section of the rod with FeCl2. Etching commences in the middle of the rods and if stopped at the right time leaves them gold centres and silver coated ends. The catalytic activity of the rods towards the reduction of p-nitrophenol at room temperature appears to be enhanced.