  Turbulence is hard to control. A plethora of experimental methods have been
developed to generate this ephemeral state of matter, leading to fundamental
insights into its statistical and structural features as well as its onset at
ever higher Reynolds numbers. In all cases however, the central role played by
the material boundaries of the apparatus poses a challenge on understanding
what the turbulence has been fed, and how it would freely evolve. Here, we
build and control a confined state of turbulence using only elemental building
blocks: vortex rings. We create a stationary and isolated blob of turbulence
($Re_\lambda$=50-300) in a quiescent environment, initiated and sustained
solely by vortex rings. We assemble a full picture of its three-dimensional
structure, onset, energy budget and tunability. Crucially, the incoming vortex
rings can be endowed with conserved quantities, such as helicity, which can
then be controllably transferred to the turbulent state. Our `one eddy at a
time' approach paves the way for sculpting turbulent flows much as a state of
matter, `printing' it at a targeted position, localizing it, and ultimately
harnessing it. Our work paves the way to gaining a complete picture of this
ephemeral state of flow.
