You must be logged in and verified to contact the designer.
This is a simple ruler that I use to measure objects in my projects. The purpose is very simple and is used in 3D software that can't export files to exact dimensions.
You just add the ruler to the project and scale it to match the object that you need to have at a fixed length. When you export the model for Shapeways, the ruler will be the longest dimensions so you can use another 3D software application to set the scale of your model to the length of this ruler (60 cm) and then cut away the ruler. You can do this in NetFabb or MeshMixer. When you scale the model to 60 cm, the object that you've measures will also be the exact length that you have selected.
This ruler isn't meant to be printed but can be printed in white plastic since it still fits the bounding box. If you do print it, you can use it to check if the 3D printer is shrinking your models or not.