/*
rotate_extrude($fn=300)
translate([30,0,0]){
scale([1,2])
circle(d=10, $fn=100);
translate([7,0,0])
circle(d=5, $fn=100);
}
*/

/*

linear_extrude(height=30,
height=30
center=true,
scale=[1,1].
twist=180,
slices=200
)
square([20,5],center=true);
*/

linear_extrude(height=100, center=true,scale=1, twist=720,slices=200)
scale([3,1])
circle(d=10);