This type of weapon is first introduced in Problem Sleuth. Like many of the weapons in the story, it is hidden away as an Innocuous Double, which in this case is a stick of lipstick.
The Homestuck version is designed to do so technologically, as Weapon/Object Duality does not exist in Homestuck outside the Midnight Crew Intermission. In fact, the narrator has even mentioned getting hysterical when talking about this weapon - a callback to Hysterical Dame, who also wielded a Chainsaw/Lipstick.
You can download the papercraft model template here: MS Paint Adventures - Kanaya Maryam's Chainsaw Makeupkind Free Papercraft Download