A fire-breathing bot

The best-selling Robosapien toy robots are made to be hacked, so we asked the guy who wrote the book on modding them to create a flame-throwing Robozilla.
A WowWee Roboraptor with a flame coming out of its mouth to toast some charred marshmallows.
The Roboraptor's flame goes about 3 inches—just enough for close-range roasting. Luis Bruno

Let’s face it—until they’re cooking us breakfast and doing our laundry, the most fun you can have with store-bought robots is the fun you make yourself. Sure, robots like WowWee’s Roboraptor (and its companions, Robopet and Robosapien) are surprisingly capable for $60-to-$200 toys, with wide ranges of motion, touch sensors and powerful software. But it’s those same out-of-the-box skills that make the ‘bots such prime fodder for hackers.

Within weeks of the Robosapien’s introduction in February 2004, tinkerers flooded the web with new tricks: programmed dance routines, crazy voices, infrared vision. Some companies threaten legal action against such amateur upgrades (cough Sony cough), but not WowWee. Its designer, Mark Tilden, intentionally gave his ‘bots tinkerer-friendly features such as easy accessibility (each comes apart with a single Philips screwdriver), a painstakingly labeled circuit board so you can see exactly what each bit does, and a cavernous crust of exoplastic that can accommodate additions like an extra micro-processor brain, an MP3 player or a butane flamethrower. Say, there’s an idea…

  • Dept: You Built What?!
  • Cost: $181
  • Time: 23 hours
  • Difficulty: easy | | | | | hard (Editor’s note: 4/5)


  • Flame on: Trigger the internal butane fuel tank by tugging the wire inside the Robozilla’s right arm socket. Snap a spark with the piezoelectric mechanism hanging around its neck.
  • Rock out: Start the MP3 player embedded in the Robozilla’s tail to hear—what else—“Godzilla,” by Blue Öyster Cult.

How it works

Read on to learn how to make your own fire-breathing, music-playing Robozilla. For more Robo tricks, pick up Prochnow’s book The Official Robosapien Hacker’s Guide (O’Reilly; 2007).


  • WowWee Robotics Roboraptor: $99.95
  • Butane utility lighter: $4
  • El Cheapo MP3 player: $20
  • Dark green satin spray paint
  • Alligator decals
  • Assorted cable ties
  • Electrician’s tape
  • Miscellaneous wire


1. Remove the batteries and disassemble all external plastic parts from Roboraptor. Mask and paint these pieces. Apply decals to plastic pieces before final reassembly.

2. Shorten the tail. Remove and discard the first movable joint from the tail. Reconnect the remaining tail pieces and attach to the main tail section. Also, inside the main tail section remove and discard the touch sensor circuit board.

3. Load a low-cost MP3 player with a copy of the song “Godzilla” by Blue Öyster Cult. Depending upon the configuration of your music player, you can trigger this song to play whenever you press one of the tail’s movable touch sensor plates or buttons. Install the MP3 player inside the main tail section. Make sure that the movement range of the tail servo doesn’t damage your music equipment. Reassemble all of the tail pieces to the main tail section.

4. Shorten the neck. Remove the two middle rings from the neck. Be careful not to accidentally cut the head’s wiring harness, neck movement springs, and head movement connection beams that are all packed inside the neck.

5. Disassemble the head. Open the head and remove the speaker and the three connection beams that control head movement. Also, remove and discard the nylon bag that connects the head to the body. You will have to increase the length of the speaker wiring harness for relocating the removed speaker into the body cavity.

6. Run the metal extension tube from the butane lighter through the neck and out the mouth. Give yourself several inches of clearance around the tip of the extension tube and the plastic mouth parts of the head. Reassemble the head and connect it to the neck.

7. Remove and discard the neck servo located in the front of the body. Install the butane fuel tank in the former neck servo’s mounting cavity. Hookup the butane fuel tank to the lighter’s extension tube. Attach the lighter’s piezoelectric spark mechanism to the outside of the neck. Drill an access hole for enabling you to reach the lighter’s gas release valve. Then release some gas, snap the piezoelectric mechanism trigger, and a spark hits the gas. Flame on!

8. Zip it up. Carefully mate the two plastic main body pieces together. Make sure that no wires are crimped and that the butane fuel tank’s line isn’t pinched or kinked.

9. Rock it. In order to have Robozilla “assume the position,” you must rotate both legs backwards. There are a number of ways to accomplish this bit of contortionism. The easiest method is to snip off the two lower screw posts on each leg servo, remove and discard the connector holding each leg’s movement beams, and mate two screw mounting holes from each leg onto two screw posts of each leg servo. There are moving screw posts and stationary screw posts on each leg servo. In order to move correctly, each leg should be mounted on one movable screw post and one stationary screw post.

10. Attach the remaining external plastic leg parts and it’s ready for show time. Lights, cameras, action-walk Robozilla around, pinch its tail for some tunes, and spark the flame. No rubber suits here nor model airplanes on wires. Just a pure hacked hybrid of the greatest movie monster of all time growing out of the skin of one of the greatest hackable robots of all time.

More assembly details

  • You can glue the main leading dorsal touch sensor plate to the main tail section for a cleaner final appearance.
  • Try to locate a butane lighter with at least a 14-inch-long extension tube. A shorter length lighter will work, but you will need to mount the butane tank inside Roboraptor’s neck.
  • In order to give your “Godzilla” recording that “concert hall” experience, connect a small audio amplifier with at least one speaker to your MP3 player. Then play it loud.
  • Connect the fuel tank’s release valve to the movable right arm. Therefore, when you move the right arm, butane gas is released through the extension tube.

This story has been updated. It was originally featured in the October 2006 issue of Popular Science magazine.