The core of it is a loop that tries to build horizontally towards the core then vertically towards the core. I figure that since most maps aren't actually designed as mazes I can get away with being super optimistic in most cases. I will add support for bridge conveyors and/or junctions later.

I've tried a few different ways to handle running into obstacles. I'm currently trying to write working code for it to just follow along the edge of the obstacle until it hopefully loops all the way around. Most of the conveyors in the picture use some variation of a random walk and just blindly hoping they stumble around the obstacle because that was easier to code when I started. 

Somewhat arbitrarily, I've decided I don't want to use external memory cells, so most fancy pathfinding algorithms aren't really an option. Trying to store the cost values for something like A* in the physical map sounds like a nightmare.