You can double-click on a point, which will open the "Values and Tangents" window. There you can can set the coordinates of the point's tangents to zero.
Cheers,
Wolf3D
contrafibbularities's post in Honeycomb was marked as the answer
Start with a disc and give it six rotation segments.
Make editable and delete 5 of the six triangles. Optimize the object.
Put the triangle in a cloner, set the cloner to radial, no radius, 6 clones.
Put this Cloner in a second Cloner to create the pattern using the Honeycomb Array.
While you got some of the basic shapes to look right, you added them in the wrong order, I think. Also, you screenshot looks like your mesh consists of NGons. With what you've got so far, you will run into problems when trying to add the circular details and the indentations.
I would probably use SDS for something like this. As a general rule, you want to start with the bigger details and then add the smaller details. In this case, however, I would actually start with the smaller details and build the mesh from there.
Just to explain the basic principle of how I would go about this, I used the detail on the top left as an example. I would start with the cross, and with a plane object. Extrude some edges to get the cross shape. Assuming the corners are a bit rounded, I beveled some points. To hold the shapes in SDS I added additional edges to those beveled areas, and down the center of the cross to have more geometry for the round indentation and for the ends of the cross, which seem to be a bit rounded as well. The edges of that cross will define how much geometry you will need for the round indentation at the center. I created that circular shape next and deleted/rerouted some of the geometry. In order to be able to create that indentation, I changed the geometry of the circular shape at the center and added control edges at the edge where the indentation would be. All you need to do then to get the indentation is move that polygon at the center back a bit.
Next I created the geometry outside of the cross shape, which resulted in that octagon shape. Now you can extrude the boundary edges, turn them into a circle (using a free plugin called Points to circle) and make some more extrusions. At this point (object on the right in the second image) the geometry still is flat. You can then extrude polygons and move the ones at the top of the cross forward a bit. Add control edges and subdivide...
The detail on the right can basically be done in the same way.
