Boolean is not making a hole, but just cutting the mesh and not filling in the sides of the would be hole. : r/blenderhelp
Easy Cleanup in Blender: Floating Vertices, Filling Holes, Zero Length Edges / Faces - YouTube
How to repair a mesh in Blender - Artisticrender.com
Blender Sculpting Tip: Fill holes - BlenderNation
Blender - How to Fill Holes in Mesh - cgian.com
Blender: Bridging Gaps and Edges/filling holes. - YouTube
Fill — Blender Manual
3d printing - Filling Hole in scanned ct - object - Blender Stack Exchange
filling holes connects unconnected islands - Technical Support - Blender Artists Community
Blender 2.8 Three Ways of Filling Different Types of Holes | Hello everyone! This is a beginner's tutorial showing you different ways to close 3D model mesh holes using the new Blender