Add MTS server style reinforced walls and roofs to the game
Two types !
1# Greenhouse effect reinforced glass (only see thru)
2# Armored Glass walls tintable or see thru and perhaps tint can be painted by player - would be awesome.
3# door with see thru window (more expensive door) with extra crystal cost.
Even if they were expensive addition like costing extra 50-100 crystal on top of the regular build cost. It would still be a good addition.