Rings

rr=0.2;
t=linspace(0,2*%pi,10);
s=linspace(0,2*%pi,41); n=length(s);
r=dup(1+cos(t)*rr,n)'; m=length(t);
x=dup(cos(s),m).*r; y=dup(sin(s),m).*r;
z=dup(sin(t)*rr,n)';
X=[x;(x+1.3);(x-1.3)];
Y=[y;-z;-z];
Z=[z;y;y];
plot3d2(X,Y,Z,[m,2*m]);