We have developed a combined focused ion beam deposition machine and scanning probe microscope which has been used to fabricate and characterize metal nanoparticles entirely within a high-vacuum environment. The focused ion beam section is fitted with a retarding-field stage which allows the landing energy of ions to be adjusted from similar to 20 to over 400 eV. The microscope has been adapted to enable the probe to be directed to the localized deposits so that the physical structure of the deposits and the electrical properties can be measured in situ.