This rat can move about in place, talk with a wireless microphone and spit acid (really just water). Watch the videos to see how he moves.
The star of the show is a latex rubber rat I found at Wal-Mart for $7. It's about 14" tall and was filled with some kind of poly stuffing. The goal is to build a movable skeleton that conforms to the inside of the latex rat. You don't have to use a rat, any kind of hollow latex creature that is flexible can be used like a cat, gargoyle, snake, bat ect... But look for something that can be easily animated. For example if the mouth has no depth to it you really can't animate that.
I had no plans drawn up for this project and created it as I went with stuff I scrounged up around the house and at home improvement stores. This is a crudely built prop with rusted bits and popsicle sticks, but hey it actually works! You will have to use your imagination to come up with substitutions if needed.
The most expensive part of this project is getting hold of a 4 channel radio control. I used one from an old RC airplane that I never could fly. It doesn't have to be fancy or programmable, look on ebay, there are deals to be found there. You could even use a RC car radio with 2 channels and just animate the mouth and something else.
If you want to see more follow the steps to see how it was done.
Here are some videos to give you an idea of what he does.
Demo of Rat in motion Video YouTube messed up the audio sync on this one. The mouth is supposed to be synced with my voice.
Internal Skeleton video
Rat shooting water Video
Putting the skin on Video
This one below is a little dark but it was from this Halloween.