Healing Non-Manifold Objects with Blender

Have a marginal STL you found on a community sharing site that doesn't slice well? This video shows a simple way to heal that STL and make it printable. After making this I learned that you can click (deselect) the camera icon in the boolean operation to avoid the "double whammy" of calculating the operation twice.
Update. See comment below. There is a 3D Printing toolbox add-on for Blender that makes this a little bit easier. It's not 100% reliable, though. You can always fall back to this method, which has proven very reliable.