One of the most popular 3D printing services is Shapeways. It can be found at https://www.shapeways.com/. This service requires the model to have a drain hole if it is hollow or else it will be considered a solid. This is to allow the support material that's utilized to be removed.
In this recipe, we'll learn how to do this using Meshmixer and a fabricated part using SketchUp.
You'll need to make a small part with SketchUp. A dowel with a 3-mm diameter and a length of about 20 mm will suffice. It should resemble the following image:
You'll also need Meshmixer and the hollow support model you made in ...