: This is the primary and most reliable source for the plugin. : You must create a free account on SketchUcation to access the download button. Alternative Link (The SketchUp Essentials)
You can download Slicer5 for free from the : Slicer5 (v5.1 or latest) at SketchUcation Slicer 5 Sketchup Plugin Free Download LINK
Once you have downloaded the .rbz file, follow these instructions: : This is the primary and most reliable