“The pen gun discovered at Logan Airport was a .22 caliber firearm which folded open to the shape of a pistol,”
I know it is frowned on here to actually read the entire article here at FreeRepublic but:
The term “pen gun,” according to the Federal Bureau of Investigations, is generally used to describe any firearm designed “to look like an ink pen.” They were also more widely used around the turn of the 20th Century for self-defense purposes, according to the FBI’s October 2018 “Artifact of the Month” entry.
There is a picture of the pen gun in question at the link.
Here is link to the FBI’s “Artifact of the Month”
https://www.fbi.gov/history/artifact-of-the-month/october-2018-pen-gun
I’ve seen reference to pen guns and pictures elsewhere. I believe they wee more modern versions.