Ok, that was great - thanks. Although not the most exciting factory, I was able to make something that quickly turned over a fast profit!
System based games are very tricky to implement as the player can literally do anything - making it difficult to control or anticipate as well as open the doors for so many unexpcted bugs. It's very impressive you were able to get what appears to be quite a robust implementation running in such a short period of time.
Obviously, if developed further the game would benefit from some actionable direction (eg: an order for a specific item or something) and the challenge could be to make it for the lowest margin. As it stands, it's easiest just to build an infinite plank generating machine and leave it at that!