I have an idea for a buildings:
Force field generator - building similar to the pylons and substations. All buildings within range (include belts, insertors, etc.) receive protection. Gererator has a limited speed of regeneration the field so the more buildings protects the slower it regenerates the field.
Mk1 - size 1x1, 7x7 range
Mk2 - size 2x2, 14x14 range
Mk3 - size of 3x3, 21x21 range

Force field pylon - creates a barrier between the two poles (wall power). Higher Mk means greater range. Only one Pylon in chain have to be powered.
