Shacktron

The Shacktron is a colossal mecha built by the Weirdmageddon resistance to combat Bill Cipher in the Gravity Falls finale "Weirdmageddon 3: Take Back the Falls".

Physical description
The Shacktron's parts is composed of several objects throughout the town. Its main body is formed from Mystery Shack and the shack's totem pole attached, (which acts as a cannon) while its waist area houses the remains of the Universe Portal. On its back, the head and neck of the Gobblewonker robot rises, acting as its tail. Its left arm contains a amber-preserved Tyrannosaurus Rex with its free head as its hand, and its right arm contains Manly Dan's logging truck as the forearm of its three-fingered hand.

It has the right leg of the Gideon-bot and power line poles for its left leg. Soos' pick-up truck is attached to the left leg as the foot. the sign for Gravity Falls can be seen on its left leg joint and a billboard for Li'l Gideon cen be seen on the right leg joint. The inside of the shack is where the resistance pilots the Shacktron, which includes control panels from Dancy Pants Revolution, viewfinders, monitors, and a power room with a treadmill.

Role in the series
During Weirdmageddon, the survivors of the event were housed inside the Mystery Shack because it was protected by unicorn's hair, which dispelled the weirdness. To get to the Fearamid and rescue Bill's captives trapped inside, the survivors agree to construct a giant robot out of the Mystery Shack to breach Bill's defenses. With Old Man McGucket's intellect, the survivors work together to gather parts and convert the Shack into the Shacktron to fight Bill and his henchmaniacs.

The survivors then arrive at the Fearamid inside the Shacktron. Bill sends out the Henchmaniacs to fight the Shacktron who all grow to giant size to match it. The Shacktron then launches its assault against the demons as the survivors inside pilot the different parts of the mech. Outside, Wendy Corduroy and Rumble McSkirmish provide additional offense blasting down enemy Eye-Bats and manage to incapacitate msot of the demons. After the Shacktron bests the henchmaniacs in battle, Bill arrives to fight the Shacktron itself, but finds himself at a disadvantage because of the unicorn hair protecting the Shacktron from Bill's attacks. While it hol While the Shacktron keeps Bill occupied, Dipper Pines, Mabel Pines, Stan Pines, Wendy, Soos, Pacifica Northwest, Sheriff Blubs and McGucket eject themselves from the Shacktron the Fearamid to free the townspeople. The Shacktron continues to battle Bill for some time and soon pins it down. However, Bill sees that only the Shack itself was protected by the barrier, while the rest of its parts were vulnerable. Bill exploits its weakness by tearing off one of the Shacktron's legs and uses it to damage the robot, sending it flying. The Shacktron is destroyed soon after by Bill, but from its remains the Mystery Shack is rebuilt.

Trivia

 * The Shacktron was called the "Shack-bot" in the Disney XD app game Take Back The Falls.
 * The Shacktron is the keyword for one of the episode's ciphers.