3D models with significant overhangs require supports in order to successfully print on Ember.
There are several terms and phrases that are important to understand when it comes to support generation. Please review the Definition of Meshmixer's Support Generation Terms prior to reading this section.
Follow these steps to create supports for your models using Meshmixer:
Select the model you want to support.
To create supports for multiple models at once:
Click Analysis > Overhangs (on the left toolbar).
Twirl open the Overhangs menu (at the top of the window), and choose Autodesk Ember from the list of printers.
Click  Generate Support. Supports will automatically be created for your model.
In the Overhangs window, you can manually add supports by holding SHIFT, clicking on your model, and dragging to the build plate (or to another support).
To manually delete individual supports, clicking on them using the following clutch keys:
Click Done to save the supports and exit.
Don’t use  Convert to Solid, as it reduces the printability of the file.
Continue on to Export to Ember...