I have followed step by step what Metamagic has shown on his website.
First I downloaded K3Dsurf: unluckily it does not work on anything newer than tiger, but for these occasions I can use my trusted Virtual box together with a very old windows XP (I think this was the last version of windows I have used in my whole life btw!)
The software comes with many built in examples, so you can play along right away. After wxaming all of them I chose this pseudo duplin becuase it looked interesting while still being easy to print. The software can export a obj file, (mind you have to add the .obj manually to your chosen file name) and you can open this directly using Cura.
As you can see the only problem is that the original obj file is HUGE, but scaling it down (in this case to 0.1) is straightforward and gives you a file you can then transform in gcode.
This is what the ultimaker has printed out, it looks good but where the raft is the surface remains irregular and sanding it will give a different finish to the object.
Then off to i-materialise to order a gold plated steel pendant.
K3Dsurf gives you the possibility to insert formulas and create your own isosurface, searching on the web I have found many interesting websites like the university of Torino or this Java based tool that gives you the possibility to modify all parameters and then obtain the function.