Following on from the other two "300 colour" thingy's, I decided to try RepRap.Me's suggestion of using translucent filament to get around the "stripey toothpaste" effect. I can confirm that it works. That is to say that the colour appears the same all around the object.
Unfortunately something bad happened about 10mm short of the intended height and I had to abort the print (which is a bit of a pain after 13 hours). So the top surface is just infill, rather then being smooth.
I've uploaded a couple of pics. One is a picture of the thing just sitting on laminate flooring, the other shows it on the printer to give an idea of the size. As you can see, it's just about maxing out my printing envelope (I feel a big Delta coming on..........)
This time, the design is my own - Just from playing around with linear extrude in OpenScad.