Craft & Design Science
Very small hollow metal spheres
metal sphere.jpg

Tiny metal spheres are needed for tiny ball valves and tiny ball bearings, which are needed for all kinds of miniaturized machines. Hollow spheres are lighter, and thus have less inertia, and thus can be made to move faster in these very small applications, where response time is often critical. But how do you make a hollow metal sphere 2mm across? Turns out you can do it with one of the lost foam processes I’m always going on about. Tiny styrofoam beads are first coated with fine metal powder and a binder, then heat-treated to evaporate both binder and bead, leaving only a fragile hollow metal powder shell, which is then sintered into a continuous shell at higher temperature. Read more over at Science Daily.


I am descended from 5,000 generations of tool-using primates. Also, I went to college and stuff. I am a long-time contributor to MAKE magazine and My work has also appeared in ReadyMade, c't – Magazin für Computertechnik, and The Wall Street Journal.

View more articles by Sean Michael Ragan