We already have optical tweezers, which allow tiny quantities of matter to be held and manipulated by beams of light. With electron tweezers we might be able to grab hold of single atoms.
A team observing how small quantities of metal behaved as they were transitioning from solid to liquid noticed something funny happened when they moved the beam of their electron microscope. The beam had already partially melted the bit of metal, creating a liquid shell around a solid inner core. When they moved the beam, though, the solid particle followed it around, 'like it was glued to it.'
Electron tweezers may shrink down the particles that people can manipulate considerably, but they have their drawbacks. Electrons have a tough time getting through air, so the tweezers would only work in a vacuum. Read more about the tweezers here.