Friday, July 10, 2009


I'm wanting to make a small movie about a mean robot alien who comes to Earth. I've been building several props for this movie. Earlier I posted the robot and a gun I made. I still need a few more items like a miniature version of the robot and a UFO. This particular item is a retro-style bomb for dropping out of an airplane. It doesn't really explode but I think I can do that with video editing and sound effects. When the button on the top is pushed, it acts like an unstable bomb ready to blow at any second with warning lights and beeping to signify danger.

Here's what the bomb might look like in action.

These are the things I used to make the bomb. A large funnel, a waste basket with fins (it came that way from Target,) old broken electronics boards pulled from a radio, clear plastic trading card boxes, some electronic parts such as blinking LEDs, battery pack, a buzzer, an ON/OFF push button and some wire. I got the electronic parts from Radio Shack for about $10.

I soldered all the positive ends of the LEDs and the buzzer to the positive end of the battery pack. I soldered the negative ends to the on/off button, and soldered the other end of the button to the negative end of the battery pack. These LEDs will blink on their own. They also make non-blinking LEDs but I didn't think they would be as exciting.

On a bandsaw I cut out just enough of a radio electronics board to fit inside a trading card box. These electronics won't do anything other than just sit there and look electronicky. I remember on the Six Million Dollar Man tv show, when they would roll back the fake skin on his arm, it would look like this.

To make a hole to receive the electronic trading card box, I pencilled off where I wanted it to go, and drilled as many holes as I could along the inside of the pencil mark.

Then I used a chisel to finish off the smooth edge of the hole. There are probably better ways to do this, but my arsenal of tools is limited.

I used some of that 2-part epoxy putty to mount the ON/OFF button into the funnel spout. Before I epoxied it in there, I roughed up the funnel spout's surface with coarse sand paper to give the epoxy something to grab onto.

While the epoxy was still soft (you have about 15 minutes) I smoothed out the top surface the best I could. This was the largest button they had at Radio Shack. I would have liked it to be bigger. Someday I'd like to expoxy a larger wooden knob onto this button to make it bigger.

I made a hinged and latched door way on the back side of the body to change out batteries when necessary. The wooden block will be screwed and epoxied behind the door, inside the body as a containment area for the batteries. That way they won't slop around all over the insides of the bomb when it's jostled. Also I used the back side of this wooden block as a place to mount the beeping gizmo.

I cut circular holes and mounted small caps inside the holes to make cup-shaped recesses. I put labels with "WARNING - CRITICAL" and "LIVE" in the recesses. I drilled a hole in the center, and mounted an LED inside each one, and put them behind clear plastic windows.

Here's a size comparison next to a weiner dog.

I hade a total of 4 LEDs so I mounted the other 2 inside the trading card box faux-electronics. The funnel and the base were screwed together with pan-head screws. The trading card boxes were mounted with epoxy putty. I had extra screws so I put them around the body to give it a riveted look.

This is after I painted it. Here's the battery door in action. The 4 screws you see around the door are holding the wooden block in place.

The paint I used is Krylon "brown metallic hammered." It looks like old iron. It's made specifically for plastic. Normal spray paint will eventually flake off as the plastic ages. Before I painted it, I sanded it to give the paint some tooth. TA-DA! It's done!
Watch this video to see it work.


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