The Disguise Kit, also known as the Spytron 3000 Disguise Kit, is the default PDA weapon for the Spy. It is an ordinary cigarette case that, in addition to six normal cigarettes, contains hidden Spy tech.
The purpose of this weapon is to allow the player to disguise as any class of either team. When selected, the disguise menu fills most of the screen, making in-game movements difficult. Players can select class disguises individually with the correct keys or switch between teams with a single key. When the minimal Disguise Kit menu has been enabled via the Advanced options menu, the player uses fewer keys to disguise, first selecting the class type (offensive, defensive, or support) and then selecting the individual class with the same three keys.
Disguising is carried out over a couple of seconds during which smoke particles will surround the Spy when viewed by another player (These smoke clouds do not appear if the Spy was completely invisible when beginning to disguise). Once finished, a line drawing of the Spy shows up briefly on the player's screen to indicate a successful disguise. The Spy's current disguise class, name, health, and weapon will then appear in the HUD. The status of enemy Medics currently healing the Spy will also be shown. The line drawing also appears when the disguise is broken. Pressing the "last disguise" button allows the player to change their disguised weapon to one from the slot they currently have equipped.
[Undocumented] The Disguise Kit now appears in backpack when viewing stock items.
Switching classes in spawn while disguised hides some bodygroups of the player's model, such as the Pyro's gas mask and the Heavy's Fists.
The BLU Spy has white cigarettes inside his Disguise Kit, despite them appearing brown on the player model.
Lag might sometimes cause the player to undisguise automatically.
Despite being unable to capture a control point while disguised as an enemy member, if a Spy disguised as an enemy member is standing on the point when it's captured, the Spy will still receive points for the capture.
Crouching and looking up while holding the Disguise Kit allows the user to "take on" the appearance of a Spycrab, a community meme.