2D object in 3D space (by Vertices)

Yeah, sure: (JSON format)
{"Vertices3D":[{"x":10,"y":10,"z":1},{"x":9.421052631578952,"y":11.736842105263158,"z":6.789473684210525},{"x":5,"y":12.142857142857142,"z":7.7142857142857135},{"x":5.285714285714286,"y":13,"z":10.628571428571426},{"x":-1,"y":13,"z":10},{"x":0,"y":10,"z":0}]}

Yes, but I think that I can do it with:
material.side = THREE.DoubleSide;