blob22

 clf;
 xmin = -5;
 xmax = 5;
 ymin = -5;
 ymax = 5;
 zmin = -5;
 zmax =  5;
 xn = 300;
 yn = 300;
 zn = 300;
 
 sc = 10;

 [x,y,z] = meshgrid (xmin:(xmax-xmin)/(xn-1):xmax,
  ymin:(ymax-ymin)/(yn-1):ymax,
  zmin:(zmax-zmin)/(zn-1):zmax);

 fz = z; # could do distortion here
 #fy=y;
 #fz=z;
 fy = y+0.008*((z-5).^2).*sin(z*2);
 fx = x+0.008*((z-5).^2).*cos(z*2);

 p = (z + abs(z))*0.5;

 r = sqrt(((fz)/4).^(p+2)+((fy)./(0.5+p*0.1)).^2+((fx)./(0.5+p*0.1)).^2);
 v = 2-r;
  
 [f1,v1]=isosurface (x, y, z, v,1);
 axis equal;
 patch("Faces",f1,"Vertices",v1*sc,"facecolor","r");
 #  from http://iso2mesh.sourceforge.net
 savestl(v1*sc,f1,["blob22_1.stl"]);