Got the factories working, as well as bringing up the factory suite when an individual square is selected. Had some problems with renderers when highlighting the squares and when placing the walls, but those issues are resolved.
(1) Make wall renderer aware of neighboring walls, sources, and towers, giving different drawings for each configuration of neighbors.
(2) Trace power paths through walls and draw color channels through them.
(3) Have creeps get absorbed by wall until walls collapse.
(4) Add in a basic shooting tower, making sure its powered. The first three towers should be a slide, an area effect, and a shooter.