Thomas the Tank Engine was built as an accessory for my son's Halloween costume. The idea was that he would ride in the back cab and I would pull him house to house. He would then hop off get his candy then get back onto the engine. A smoke machine, fake fire, and an air whistle were all tucked away inside the engine.

Supplies

1/4 plywood
paint
tape
foam
cardboard tubes
whistle
fake fire
smoke machine
caulk
12vdc battery
12vdc fan
train whistle
air tank
ball valve
spring

Step 1: Building the Shape.

To get the shape I used a small Thomas the Tank toy. I scaled the measurements and roughed out the shape with cheap plywood. I used cardboard tubes that typically are used to poor concrete foundations. The frame that carries the engine was an old bed frame. I cut and welded the bed frame then added axle and wheels. The train did not have any steering system, the plan was for me just to drag it left or right with my pull bar. Inside the cab you can see small doors that open to the "fire box". This "fire box" area will hold a fake fire that is from an old broken halloween lantern.

Step 2: Paint

Painting the engine is much like any project you paint. The colors were easily matched from our local hardware store. I used masking tape to cut better paint lines. I also used a wide masking tape to cover any edges that would show a seam. That tape would wrap around the edge leaving half on one side and half on the other. This cheap option avoids extra work blending edges together. Just tape where two boards join and pain over.

It's a fact that children will get paint in their hair. Be prepared!

Step 3: Add Accessories

When I make projects I like to add a little extra to get a reaction from onlookers. For this project I thought it would be appropriate to have smoke coming from the smoke stack, fire in the fire box, and a train whistle.

The smoke is from a small smoke machine tucked into the main train body. The smoke machine need 120vac so I needed to add a power inverter and 12vdc battery. The 12vdc battery would also be used to run the fake fire.

The fake fire was from an old halloween torch. A red light was mounted to shine on a cut piece of fabric made to look like fire. When a fan is placed underneath, the fabric flaps looking like fire. I mounted this fake fire inside the two doors in the cab. (Seen the video)

When using a smoke machine, you must remember that a smoke machine does not move air like a fan. In fact the smoke machine uses no fan at all. The smoke machine is heating liquid until it turns to a smoke. The smoke passes out of the heating chamber through a small hole. The warm smoke will rise due to its temperature. In this project I needed to drive the smoke up and out of the smoke stack. I used a small 12vdc fan to direct the smoke up and outward.

Unfortunately, I built this project years before Instructables existed so I only took general photos and don't have photos of the train whistle assembly. The train whistle was a wood toy train whistle(some photos show mounted between round windows). Air passes into a tuned chamber and creates a train whistle sound. To solve this I used a pressurised tank of air, copper lines, and a ball valve. I mounted everything and modified the ball valve to close automatically with the help of a spring. I tied a string to the ball valve handle so pulling it would allow air to leak out of the tank.

Step 4: Pack It Up and Go Trick or Treating.

After the tank was done we got the kids dressed and took them to a neighborhood. I pulled my son door to door so he could get his candy. He blew the whistle when it was time to go.