Platinum is a naturally occurring element found in the Earth's crust. It has an atomic number of 78 (78 protons and 78 electrons). Platinum is a metal (technically it is a transition metal) and is often mined as a pure metal or alloyed with iridium. It has many uses (aside from being a precious metal) including catalytic converters, electrical contacts, and chemical catalysis.
There are 6 naturally occurring isotopes of platinum: 190, 192, 194, 195, 196, and 198. Pt-195 is the most common one found in nature (33%). There are 31 synthetic isotopes of platinum ranging from 166 to 202. The one you are asking about (Pt-166) is the least stable isotope of all with a half life of only 300 microseconds. While I could not find a specific "recipe" for synthesizing Pt-166, I can tell you that synthetic radioisotopes are commonly made using particle accelerators. These devices propel atoms at high speeds using magnetic fields to smash atoms against each other to create new, non-natural atoms which are generally very short lived.