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DIY Weekend: Trigger finger opens this gun safe

Greg Gilmour wanted to keep his gun safely locked up, and he wanted to do it the way James Bond would, so he went the homemade biometric-safe route.

Biometric gun safe
Biometric gun safe: For your hands only...
Greg Gilmour

Greg Gilmour is a tinkerer. He's also a gun owner. He had his mind set on a biometric gun safe, because Greg is a responsible geek, and, after all, such weapon storage "is something straight out of a James Bond film," he says.

If you're not familiar, a biometric gun safe is simply a safe that's unlocked with fingerprints. No keys, no passcodes, no PINs--just your fingerprint. It's a secure way to go.

The thing is, they're expensive. Being something of a geek like the rest of us here at Crave, Greg thought that he could build his own. And he did.

He found a Craftsman Fingerprint fingerprint-reading garage door opener in a clearance bin. He reasoned that the scanner simply scans a print and, if recognized, sends a usable signal to a switch that opens the door. He figured he could find a nonworking pistol safe that would take just such a signal. And he was right: a little digging on eBay scored him an electronic gun safe with a broken keypad.

He had both parts of his biometric gun safe in hand, and now he had to put it together.

Using some off-the-shelf diagnostic tools, Greg, who lives in Iowa, found the part that sends a signal to the transmitter of the garage door opener. It sends a signal only when a fingerprint is a positive match. That was perfect. The only hiccup was that the reader also sent a pulse when turned on. That pulse would trigger the lock, meaning a thief would simply have to reset the thing to get the valuables. That's no good.

So, when faced with a problem, Greg did what any good geek would do: he went to the Internet. And the Internet told him that he could easily program and implement an Arduino microcontroller to differentiate between the on signal and the positive-match signal.

After a tutorial and a few lines of code, Greg was good to go. The scanner passes the affirmative signal to the lock via the Arduino. The Arduino takes the signal, and if it's above a certain strength, it passes it on to the lock, which triggers and allows the safe to open.

It requires two sets of batteries--one for the lock and one for the scanner--but it was cheap, it works, and more importantly, it's way cool.

For more info, including a schematic so you can make your own, check out Greg's Web site. Now, here's a video of the thing in action:

To share your DIY project, simply e-mail a description of 350 or fewer words, including all the geeky ins and outs of your invention, plus relevant links and photos, to crave at cnet dot com. Please put DIY Weekend in the subject line.