3D Printed Pendant for Shapeways

I have created a 3D pendant for upload to Shapeways. It was a simple job to create the original pendant in Blender, but getting it ready for upload was a little more challenging. I tried exporting to an stl file and then just hit upload, but it turned out there was a little more to it than that. This article on the Shapeways blog, for example, gives some tips and hints. As the post says:

 ...scale your objects to the size you want, assuming 1 blender unit equals one millimeter. 

This is very important, because it tells shapeways whether the 3d object is watch strap or a wedding ring. Unfortunately, all the tutorials I looked at were rather vague about the details of finding out how big the model is, in Blender units. This forum thread goes into more detail and it was helpful but still vague. This tutorial on turbofuture was where I actually found out where the dimensions where in the Blender interface. They are among the settings that appear in the right of a 3d window when you hit N.

The next problem was that the dimensions displayed the largest length (the Y axis) as 40mm - which is great because that's what I want, but displayed the shortest length as 10m. Hang on that can't be right!

It turns out that this is intentional, according to another forum - you have to switch to "global" transformations in the settings we made appear in the panel that popped open when we pressed N. With all that done, all I had to do was keep slightly increasing the thickness of details until the Shapeways algorithms decided it would print out well, and now - it's for sale. So go buy it at Shapeways and hang it round your pretty neck for the world to enjoy.