import graph3;

size(8cm);

currentprojection=perspective(
camera=(10.0727817501153,3.74298428635732,8.52398607861811),
up=(-0.0297367955490125,-0.00628656900952393,0.0232777528581501),
target=(2.23313907154483,2.16099419927418,-1.91821818048332));

patch p1=unitfrustum(0.5,1),
      p2=unitfrustum(2,3),
	  p3=unitfrustum(4,6);

draw(surface(p1),blue);
draw(surface(p2),white);
draw(surface(p3),red);

limits((-2,-2,-2.5),(3.4,3.3,1.5));
xaxis3("$x$",Arrow3); 
yaxis3("$y$",Arrow3); 
zaxis3("$z$",Arrow3);