Form of utility fog which, in its dormant state looks like a puddle or pond, and has the rough consistency of pudding or thick soup. This is self-repairing technology which, when not needed, withdraws into a 'feeding' reservoir where its energy needs are cared for. Properly designed, there can be a constant slow stream of utility fluid going back and forth from this reservoir and replacing bits which are tiring.
Utility liquid carries with it a fluid matrix which acts as a coolant as well as an energy conduit; the outermost layer of utility liquid is capable of forming a membrane, similar to surface tension, although this layer can be dissipated quickly if necessary, or reinforced to form a rigid shell. A common utility fluid design is a dynamic hydrogel. Fibril-like micro-bots arrange themselves in the liquid giving it a pseudo solid state thanks to the extreme surface tension. Adjusting their shape and configuration can adjust the apparent movement and viscosity of the fluid. At lower viscosities the less control the fibrils have over the fluid. At an extreme the bots can form one bubble layer around the liquid, if the total mechanical strength is sufficient for the fluid's mass.
Utility liquid can form solid shapes which are capable of supporting external objects, and if necessary these shapes can be reinforced internally using diamondoid or similar ultrastrong materials, allowing significant structural integrity.
The outermost layers of utility fluid can be reconfigured to project images, and can transmit sounds and haptic sensations to a user embedded inside the fluid. Such a user can experience a completely (and literally) immersive virtual environment inside the fluid, while the fluid also supplies breathable air (and olfactory stimuli if required).
One common use of utility fluid is to surround and protect a user who is subject to extreme acceleration and sudden shocks. A spacecraft compartment, or a spacesuit, may be completely filled with utility fluid which immerses the occupant or occupants in a suitable and safe environment, which may either display navigational and tactical information or a virtual environment for entertainment. The physical needs of the user can be taken care of by the gel, while providing any pharmaceutical input if required (for neurological augmentation or recreational purposes).