CTRL+A is to be used in Object Mode with an object being selected, it allows to “apply” the transformation (rotation, scaling…) you have done in - Object Mode - (as when unapplied it will impact many edit mode tools, something you may want in some specific cases, but not there)
Note, if you have done the transformation in - Edit Mode - you do not need to apply them, they’re applied automatically.
CTRL + N is to recalculate the normals of your object in edit mode.
Blender does very badly regarding normals when you extrude or remove doubles, it’s supposed to have been improved (i had reported it as a bug during the RC tests of 2.71) but from what i see that fix didn’t made it for some reason into the “stable” 2.71 as i got the same bad results regarding normals even in simple extrusion, so you’ll have to press select all and press CTRL+N often when you’re extruding anything
Now for curved object, you can use the Curve modifier to make a mesh follow a curve.
But an alternative could be this .
When you’re at that point of the tutorial up there
- Press CTRL+I to invert the selection and press X -> Faces to delete it
Stop after having done this, then :
Create the curvature as a mesh, there i am using a sphere bellow both the honeycomb and the mesh i used to “knife project”
Go to top view, select the honeycomb and in the bottom header enable the Snap button (the magnet icon) , set the snap to Surface , closest and enable the 2 buttons that are next to it :
Select all , then press G then enter or left click to validate, this will project the whole selected mesh on the surface of the object behind it (the curvature i need) , this will give the curved honeycomb i need.
Do the same for the object that has been used for knife projection, (though you may want to hide the honeycomb object by selecting it in Object Mode and press H) go to top view, select it , go to edit mode, make sure the same snap tools are setup and enabled, then press G , then enter/left click to validate.
Once done, disable the snapping tool (the magnet icon) or Blender will always try to snap things on surface of other object when moving anything
Back to object mode, unhide the honeycomb object (ALT+H) , and you should have both the honeycomb and the object curved as needed .
From that point you can resume following the previous tutorial
Note : if when projection the honeycomb on the surface of the curved object you notice the honeycomb does not curve that nicely, you may need then to select all the honeycomb and press the Subdivide button (or W -> Subdivide) in order to get more geometry and allow the honeycomb to snap more nicely in the curved object (on my test i didn’t needed to subdivide, the curving was nice)