The Glowstone Illuminator is one of the lighting blocks added by Thermal Expansion. The block's color and response to Redstone signals are both highly configurable. The Illuminator can be crafted into six different shapes, some of which can be rotated and/or placed on walls or ceilings.
Illuminators can be moved around without losing their configuration by dismantling them using a Crescent Hammer or similar. Redprints may also be used to copy the configuration of an Illuminator to other Illuminators or Lumium Lamps.
The Glowstone Illuminator can be in one of several modes in how it responds to Redstone signals. These modes can be cycled through in the Illuminator's GUI or by using a Crescent Hammer on it.
The Glowstone Illuminator can be configured by sneaking and using a Multimeter on it. The Illuminator's GUI is then opened: