Building "The Luggage"

Artwork by Paul Kidby

"...half suitcase, half homicidal maniac"

What is the Luggage?
The Luggage is a beloved character from Terry Pratchett's Discworld novels. It was introduced in the first book of the series "The Colour of Magic" and was originally owned by the Discworld's first tourist, Twoflower. Later in the story, Twoflower gives the traveling trunk to the "Wizzard" Rincewind in thanks for his assistance as a guide and friend.

Made of magically impervious sapient pearwood, The Luggage's function is to act as both a luggage carrier and bodyguard for its owner, against whom no threatening motion should be made. The Luggage is fiercely defensive of its owner, and is generally homicidal in nature, killing or eating several people and monsters and destroying various ships, walls, doors, geographic features, and other obstacles throughout the series.

Its mouth contains "lots of big square teeth, white as sycamore, and a pulsating tongue, red as mahogany." The inside area of The Luggage does not appear to be constrained by its external dimensions, and contains many conveniences: even when it has just devoured a monster, the next time it opens the owner will find his underwear, neatly pressed and smelling slightly of lavender. It is unknown exactly what happens to anyone it 'eats'.

Building the Luggage
In construction of The Luggage, every effort was made to adhere to the descriptions given in the books as well it's interpretation in the Skyone television series "The Colour of Magic/The Light Fantastic." Some things however, were completely impossible to do technically or simply illegal, such as jumping up and down, swallowing people whole, and interdimensional transit.

The items I were able to accomplish are the following:
  • It's pretty much lifesized and mostly accurate in detail
  • It's got moving feet (although I was only able to squeeze in 24 of the buggers)
  • It's made of real wood (Sorry! Home Depot was out of sapient pearwood at the time)
  • It's got "teeth" and a "tongue"
  • It's completely remote controlled via eight hidden switches in Twoflower's "Iconograph"
  • It can "sit" and "stand up" by raising and lowering itself over it's "feet"
  • It can run about in eight different modes of movement (forward, reverse, forward/left, forward/right, reverse/left, reverse/right, turn on axis right, turn on axis left)
  • It can open and shut it's lid/mouth on command
  • It groans and creaks on command
Construction Notes
Cost and Time
About three months of work was put into this project. Total cost was under $500 as I already had the two scooters and the motors.

Why Do This?
IT'S THE FREAKING' LUGGAGE IDN'T IT??! I figured no one had done one that was "fully" functional, and that was a project within my limited capabilities.

But mostly, it was made to amuse Sir Terry at the 2011 NADWCON in Wisconsin. I figured if it could give him 1/100th of the joy his books have given me, it would be well worth the effort.

The Drive Platform
The Luggage is actually driven by two 10" rubber wheels, each with an independent motor. A freewheeling castor provides a third wheel to provide stability. The feet simply hang off the sides of this platform using pivoted levers and freespin on their own as they touch the ground, using their own weight to hold them down.

This arrangement gives the luggage complete freedom of movement, including the ability to turn like a tank. The motors, wheels and belts were provided by two 24v electric scooters donated to the cause. In addition, a scooter's PWM controller was used to provide a preset the speed control for the system.

A custom made, high-amperage Rheostat was needed to control bias between the two motors. Without it, it would be impossible to get both motors to push the unit in a straight line when going forward or in reverse. The rheostat can handle an estimated 30amps before getting hot. However, the total amperage draw is about 2 amps at low speed, with spikes around 15amps at start and stop.

The platform is powered by four 12v 4aH lead-acid batteries. With the current power consumption level, it can run for days without a charge.

The Feet
The feet were individually cast and then sculpted in two-part urethane foam. They are very lightweight, yet are rock hard. In addition, the soles of the feet are doped with a rubberized coating to provide additional protection and to grip the floor better. There are both "right" and "left" feet in alternating positions on each of the six "feet-wheels". There are three "feet-wheels" on each side of the platform. Each "feet-wheel" contains four feet. Thus, a total of 24 feet were made.

The plaster-of-paris mold was cast around a carved styrofoam "plug." Then, the mold was filled with two-part urethane foam which hardened in about 15 minutes. The result was then cleaned, sanded and attached via wooden dowels to the cubical "hub" of each "feet-wheel."

The Trunk
The trunk is made of a cedar skeleton with oak luan sides. The strapping is made from PVC slats found in window blinds. It was designed to be very lightweight and only weighs about 20lbs. It is mounted to the drive platform via four vertical dowels mounted near each corner. The dowels ride inside four corresponding PVC pipe cylinders on the drive platform. Large springs are inserted around each dowel to provide additional lift. This arrangement allows the luggage to go up and down, yet also be attached to the drive platform.

A windshield wiper motor mounted on top of the drive platform swings a wheeled lever which pushes the trunk upwards from the center. This also allows the trunk to pivot around this point freely, lending a very biological feel to the way it moves.

The Mouth
The mouth opens and shuts via a geared motor harvested from an old Pool cleaning robot. It spins a lever which pushes a pushrod attached to the right side of the lid. Additional lift is provided by a pushrod on the other side which is spring assisted.

The teeth are made out of the same PVC blind material as the strapping. The tongue is made from a red terrycloth towel.

The Remote Control System
The luggage is controlled via hidden buttons in the floor of the "Iconograph" Twoflower carries with him. This allows me to control the luggage somewhat surreptiously. Two four-channel remote control cars were purchased at Target for about $10 each. One is at 27Mhz and is used to control the drive platform, the other is at 49Mhz and is used to control the special effects. Each circuit is directly attached to four reed relays, which in turn run the larger relays that drive the higher amperage equipment. The relay circuits are all custom designed by myself.

I am particularly proud of my relay circuit that provides eight modes of movement with only four 4PDT relays and two diodes. It's logic is complex, but its a very simple circuit to build.

The Iconograph
Almost as much work went into the design and function of the Iconograph as went into the Luggage. Everything is handmade in a very steampunk style, including the box and all accutriments. There is a working eyepiece lense on the top of the box which can see out of the front via an internal 90 mirror and lense system. The large lense in the front is out of a projection television and the medium sized lense was recovered from some old telescope optics I had laying around. All the brass fittings, knobs and gears were also from found materials.

Besides the control system in the lower half of the box, there is a highly detailed interior containing the "picture imp" and his work room. The work room contains furniture, pots and pans, a wash basin, food and his paints and easel. The "Imp" is made from a wooden mannequin, with custom carved balsa wood head and hands. He also wears handmade clothing.

He ALSO TALKS! By pressing a secret button, he says "It's no good. I've run out of pink. No pink, See? No good you going on pressing the lever when there's no pink, is there? If you wanted pink you shouldn't of took all those pictures of young ladies, should you? It's monochrome from now on, friend. Alright?."

It Really Takes and Prints Pictures
Hidden inside is a small Canon Digital Camera which looks out of the upper-right lense hole. It's connected via USB to a Polaroid Pogo Zink Printer (about the size of a pack of cards). Since the camera supports PrintBridge, no computer is necessary between the two. Using CHDK, I hacked the firmware of the camera to automatically invoke the PRINT function shortly after taking the picture automatically. The Lever on the side closes a contact which is hardwired into the camera. When the Enchanted Lever is pressed, the firmware detects the signal, takes the picture and prints it.

The software also sets up the proper settings, zoom, focus, etc when the camera boots. Really neat! I can take about 10 photos before I have to remove the camera and refill the printing paper which is about 3"x2"in size.

Luggage Construction Schematics

Luggage Construction Photos

Luggage Construction Movies

Iconograph Photos

The 2011 North American Discworld Convention
We participated in the NADWCON Masquerade this year and took home two awards!
I won the Cunning Artificer's "Leonard of Quirm" Prize as well as the "Prop Workmanship" award for excellence in Iconograph and Electrical Engineering.

The convention was a hoot. Man, those Seamstresses know how to throw a mean party! The Luggage and I must have posed for over a hundred photos. As I was so busy, I wasn't able to take many of myself. If anyone has and photos/videos to share, I'd be most appreciative!

I only wish I could have stayed longer. Neil (FREAKIN') Gaiman came in a few hours after I left as a surprise during the "Good Omens" talk Sir Terry was to give. From what I've seen of the Youtube coverage, having both stellar writers in the same room was amazing.