Even if you've got the table, some choice paddles, and enough room to play, a game of ping-pong can still be undone if you can't find a tiny plastic ball that isn't dented. Table tennis balls are notoriously easy to damage, rendering them useless to play with, which is what inspired Philipp Günther to create the nearly indestructible 3D-printed AirBall.
Modeled in 3D and then printed in plastic, the AirBall's delicate lattice-work structure makes it appear frail and easy to damage, but it's made from a sturdy material that maintains its shape, even after being flattened. So you could carry it around in the tightest of jean pockets, and still be able to pong as soon as you fished it out.
However, since the printing process is so important here—after all, the balls have to be perfectly spherical to play with—Günther is actually selling them through a crowdfunding site instead of simply releasing the 3D plans. At $27 for a three-pack the AirBalls are obscenely expensive compared to regular old ping-pong balls, but, at least in theory, they should last forever. Unless an unforseen act of dog turns them into shredded plastic. [Cut&Paste via 3ders]