Since the 19th century, people have been disguising guns to look like other things in order to easily conceal them. Guns were built into canes, lighters, belt buckles, watches, jewelry and all kinds of every-day items. One that was common in the 1920s, according to this story on Guns.com by Chris Eger , was the pen gun. it was generally the same size as a fountain pen of the day but capable of firing a single handgun round, usually a soft-hitting .22.
They were later used by spies during WWII and the Cold War. James Bond used one in “Never Say Never Again.” But for the average citizen, a pen gun could win you 10 years in prison if it’s not registered with the BATFE as an AOW (Any Other Weapon) under the National Firearms Act.
The Stinger pen gun bypasses all that because of a quirk of its design. From pen form, it must be twisted into the shape of a pistol before it can be fired. This actually qualifies it as a pistol under the BATFE rules.
When in pen mode, the Stinger is just under six inches in length and about the thickness of a Sharpie marker, weighing 5 ounces with a 2-inch barrel. They were produced into the early 1990s and came chambered for .22LR, .22 Magnum, .25 ACP, .32 ACP, and .380 ACP ammo. It has no sights and was basically a point-blank weapon that took two to three seconds to convert from pen mode into gun mode, so it’s practicality and applications were limited. It also had to be disassembled to reload its single round.
A company called R.J. Braverman Corporation became manufacturing the Stinger in 1991, but folded in 1997, according to the story. In 2002, a new firm formed as the Stinger Manufacturing Company in Michigan, but they too folded for good in 2004. Today, Stinger rimfire models typically fetch $500 whereas those chambered in .32 and .380 sometimes go for twice that.