>	with(plots):

Warning, the name changecoords has been redefined

>	RightHalf:=implicitplot3d(x^2+z^2=(4+sqrt(1-y^2))^2,x=-5..5,y=-1..1,z=-5..5,scaling=constrained,axes=boxed):

>	LeftHalf:=implicitplot3d(x^2+z^2=(4-sqrt(1-y^2))^2,x=-5..5,y=-1..1,z=-5..5,scaling=constrained,axes=boxed):

>	display(RightHalf,LeftHalf);