How to Make a Putt-Putt Boat With Copper

Repurpose almost any type of material for this boat.

Harness the power of heat by making a putt-putt boat out of copper. A putt-putt, or pop-pop, boat is a toy heat-powered boat that can be fabricated from any type of material. Coiled copper is heated to produce an engine that moves the boat through the water. Craft your own putt-putt boat by repurposing an old milk carton, and use copper tubing to make a vacuum that draws and pushes water through its motor.

Things You'll Need

• 1/2-gallon milk carton
• Scissors
• 1/8-inch thick 12-inch long copper tubing
• Vise
• Oxyacetylene torch
• Pliers
• Gloves
• 1-inch thick round metal bar
• 2 1/8-inch thick 3 1/2-inch long copper tubing
• 2 1-inch thick 3-inch long copper tubing
• Flux paste
• 35-watt soldering iron
• 1/32-inch tin/lead solder
• Clear silicone sealant
• Votive candle

Instructions

1. 

   Clean out your milk carton before you use it.

   Cut the half gallon milk in half lengthwise with scissors. Use one of the cut pieces to form the hull of the boat. Choose the side in which the spout is closed to prevent constructing a leaky boat. Set aside.

2. Clamp 1-inch of one end of the one-eighth thick, 12-inch long copper tubing in the vise. Start up the oxyacetylene torch. Heat up the entire length of copper tubing to soften it up for shaping. Allow it to cool.

3. Bend the center of the copper tubing into a loop using pliers or gloves. Once it hardens up again, heat the tubing with the torch. Allow it to cool and bend it into four more loops. Remove it from the vise. Place a 1-inch thick round metal bar onto the vise. Push the looped copper tubing onto the metal bar and pull at each end of the tubing so the five loops are evenly spaced in the center of the tubing.

4. Clamp one of the 1/8-inch thick, 3 1/2-inch long copper tubing. Heat one end and allow it to cool. Gently bend 1 1/2-inch of the end upward at a rounded 45 degrees. Repeat with the other 3 1/2-inch long copper tubing.

5. Wipe flux paste onto all the ends of the tubing you bent and the two pieces of 1-inch thick, 3-inch long copper tubing before your solder them together. Place the 1-inch pieces at each end of the coiled long tubing. Then push the 45-degree bent tubing into the 1-inch pieces so they bend the same way. Cut small pieces of one-thirty second inch tin/lead solder and solder them onto each joining copper tubing with the 35-watt soldering iron.

6. Poke two small holes approximately 3 inches apart on the inside bottom of the hull with the tip of the scissors. Push the two legs of the coiled copper tubing the soldered through these holes from the top. You must bend them slightly to fit through and the legs end up under the hull. Leave space to place a votive candle under the coil.

7. Seal around the holes in the hull with clear silicone sealant, and allow it to dry. Place a votive candle under the copper coil inside the boat. Light it and watch the boat go.

Tips & Warnings

• A boiler can be crafted with a small can and placed over the coil and candle. This acts as a flame guard as well.

• Experiment with different boat hulls made from metal cans or soldered aluminum pie pans.

• Use the boat in large bodies of water rather than a bathtub.

• Adults need to supervise and guide children with this craft. Use care when using the blow torch, soldering and lighting the candle.