Well, I knew it would be a relatively simple project, although turned out to be a little more time consuming than i expected to get everything together and working. Unfortunately, I don't have pictures as I was making it because I just made it and only thought about this afterwards... maybe I'll remember to take pictures when I make the next ones.

There are plenty of instructions (and instructables) for making a bristlebot (e.g. http://www.evilmadscientist.com/2007/bristlebot-a-tiny-directional-vibrobot/ ), so I won't put too much time into that, basically I just made a bristlebot, but used 2 button cells instead of the coin cell so they would fit inside the rats. I also wired a simple switch in series (to turn them off and save the battery) and the plan was an LDR in series as well so it would appear that they would run away from the light.

My son had a lot of fun playing with the one I made, but the batteries did not last too long. (I might have shorted them when I was making it, which would not have helped.) I tried to take some pictures while I took the thing apart since I would have to dismantle the entire thing to replace the batteries, but the pictures were all blurry and useless.

It moved slower than I would have liked, but I'm definitely going to make more. Unfortunately I have a couple of other projects which take priority and need to be completed before Halloween (in 3 days) so I might not have time this year. This is part of the reason for writing up the project so I remember what happened so hopefully for next Halloween I can make a whole swarm of these rats.