Mexican Hat

Mathematical equation "Mexican hat"
implemented in Matlab
[x,y] = meshgrid(-8:0.1:8);
r = sqrt(x.^2+y.^2)+eps;
z = 5.*sin(r)./r;
surfc(z), shading flat
surf2stl('C:\Users\Gerardo\Desktop\mexicanhat.stl',x,y,z)