Fixing a non manifold STL using Blender for 3d printing

I show you how to activate and use a built in add-on to fix broken non-manifold stl files in Blender for 3d printing. :2.6/Py/Scripts/Modeling/PrintToolbox I'm a 3d artist who usually uses 3ds Max (since 2007) but I am slowly transitioning over to Blender. I started 3d printing about 3 years ago and am building a couple of new printers a Hypercube by Tech2c and a Prusa i3 mk2s clone. I also help moderate the 3d Printing Australia Facebook page. I also try to make ukuleles when I have time, in wood, but have also designed a 3d printed skeleton Uke that is on hold atm. I recently fixed my long running audio issues only to now have my video editor HitFilm decide my recorded avi screen capture shouldn't be allowed to load. So I downloaded Virtualdub to edit and compress it but it decided to make a 300 mb 11 mins film into a 30 gb one. I reset