Originally published on metropolis.co.jp on April 2011

You’ll need to have a pachinko ball on hand (or a pocket of coins) for this, but it’s a handy trick if you’re stuck in a blackout scrambling for flashlight batteries. After a rummage, you finally find some AAs. Great—except the flashlight takes those fat C batteries. Fret not, for this “Tech Know” tip can help you light the way. Wrap the battery in paper to increase girth, seize a pachinko ball from your bucket to add some length and presto—an improvised C. Non-gamblers can use eight ¥1 coins. Failing that, even a ball of tinfoil will do. Clever, eh? If you fancy giving this a whirl, let us know how you get on, by writing to letters@metropolis.co.jp.

Source: http://meturl.com/batterysize (Japanese, but with good diagrams).