Stardust Brick

Every brick you press is a fragment not going into a weapon, so hold off until your gear is settled. After that the Pillars keep restocking you and this becomes a block you can afford to use by the thousand.

The pale blue glow is soft enough to build a whole interior from without the room feeling lit up. It suits an observatory or a sky base, anything meant to read as cold. Because it lights itself, long corridors made of it stay visible with no torch line, which matters more than it sounds when you are running a hallway between farms.