We recently had a spate of doodle bots entered as projects for various reasons, and we never have a shortage of line followers in the queue. I have never seen anyone attempt to make one follow the other. It would be amusing to me for about 39 seconds I think. Especially if the doodle to were programmed to draw its line in a random way and if there were multiple line followers-kind of like a row of ducklings. Video would be great with an electronica version of the "Bridge Over the River Kwai" march.
(This is a 2 am post. I bet I regret it when I wake up tomorrow.)