Square - Octagon - Circle - Modelling puzzle I'm trying to make a rubber mat that is basically a big flat cube with lots of little holes (cells). It makes sense to me to model each cell and use an array modifier to construct the overall mat.

The problem I'm having is one i frequently run into in other areas too, which is how to add geometry as you go along without creating shading issues.

In this particular example, I need to go from a square outer edge (4 verts) to an octagon (8 Verts) into a circle ( I can get away with 16 verts). I've done this by a combination of extruding and subdividing, which works okay(ish) but generally creates shading and edge loop issues.

My question is - Is there a proper way to perform this kind of extrude and subdivide modelling? Or am I going about it the wrong way completely?

Many thanks in advance!

Sam
in my opinion you are going fine, remember that there are many ways to achieve what you want in Blender, so in this case I see two other possibilities.

Option one: 

You can add the flat base geometry.



Select and erase these vertices



Add a mirror modifier like this





And then extrude





Option Two:

Use Boolean

Add a cube



Add a 8 vertices cylinder



Add a Boolean modifier to the cube like this



To look the cylinder in wireframe only, go to Object menu > Display > and set Maximum Draw Type to Wire



Repeat the previous steps with the other geometry, at the end you will have something like this



Now when you're ok with the look, just apply the modifiers and done.