Mathematically defined rocket ship

This is a demonstration of an open source tool chain to produce an object defined by a formula.

I used the following Octave script to make the stl file:

clf;
[x,y,z] = meshgrid (-2:0.05:2, -2:0.05:2, -2:0.05:2);
kr = -0.5;
v= (x.^2 + y.^2 + ((z - 1.)*0.5).^2).^kr ...
+ ((x - 0.943).^2 + (y).^2 + ((z + 0.333)*0.5).^2).^kr ...
+ ((x + 0.5).^2 + (y - 0.816).^2 + ((z + 0.333)*0.5).^2).^kr ...
+ ((x + 0.5).^2 + (y + 0.816).^2 + ((z + 0.333)*0.5).^2).^kr;