Knife cut with closed sides like boolean difference does I am using knife project to cut holes into an object. Is there a way to close the sides of the cut so I cannot see the hollow inside of the remaining part?



I created the second picture using boolean difference, but it would be very convenient to use the knife tool.



thank you!
The Bridge Edge Loops function provides a powerful tool to close these holes: https://docs.blender.org/manual/en/dev/modeling/meshes/editing/edges.html#modeling-meshes-editing-bridge-edge-loops 

It is worthwhile to play with its many options.